We look at all the Round 12 action
With just three rounds left in the Pro12, and therefore only a maximum of 15 match points left to play for, the competition for a top four finish will intensify over the final weeks.
Leaders Glasgow Warriors face a tough trip to Llanelli on Friday to play Scarlets as their hosts are themselves vying for a top four finish, so both teams will be determined to come away with the points.
Following their impressive victory at the RDS, second placed Ulster now face a home game against Newport Gwent Dragons to keep up their Pro12 challenge.
Ulster will be looking to catch up with leaders Glasgow who they trail by just one point.
Leinster are the third team challenging for one of just two home play-off spots, and they have the formidable task of taking on interprovincial rivals Munster at Thomond Park on Saturday. However the visitors will be buoyed by the fact they came away with the points on their last visit.
Also on Saturday the remaining team in the play-off zone, Ospreys, welcome Benetton Treviso to the Liberty Stadium.
The Italians may not have won at the venue, but are on a three match winning streak, so Ospreys will have their work cut out to make sure they keep ahead of Scarlets in the table.
We look at all the Round 12 action!
Friday, April 12
Scarlets v Glasgow Warriors
(Parc y Scarlets - Kick-off: 19.05; 18.05 GMT)
Scarlets have lost just one of their last seven matches in all competitions: 5-32 to Leinster at the RDS in the Pro12 on 23rd February.
The Llanelli based side have won their last four encounters at Parc y Scarlets, Scarlets are going for a clean sweep over Scottish opponents this season.
Glasgow Warriors only loss in their last nine PRO12 fixtures was 17-22 to Leinster at the RDS on 23rd March.
The Warriors have won eight of their last nine encounters with the Welsh regions.
Glasgow have won just one of their last five matches against the Scarlets: 19-9 at Firhill in February 2012. Warriors have not won at Parc y Scarlets since May 2010.
Scarlets: 15 Liam Williams, 14 George North, 13 Jonathan Davies, 12 Scott Williams, 11 Andy Fenby, 10 Owen Williams, 9 Aled Davies, 8 Rob McCusker (captain), 7 Johnathan Edwards, 6 Aaron Shingler, 5 Johan Snyman, 4 George Earle, 3 Samson Lee, 2 Ken Owens, 1 Phil John.
Replacements: 16 Matthew Rees, 17 Rhodri Jones, 18 Deacon Manu, 19 Sione Timani, 20 Josh Turnbull, 21 Gareth Davies, 22 Aled Thomas, 23 Gareth Maule.
Glasgow Warriors: 15 Stuart Hogg, 14 Sean Maitland, 13 Mark Bennett, 12 Peter Horne, 11 DTH van der Merwe, 10 Ruaridh Jackson, 9 Henry Pyrgos, 8 Ryan Wilson, 7 John Barclay, 6 Josh Strauss, 5 Al Kellock (captain), 4 Tom Ryder, 3 Moray Low, 2 Pat MacArthur, 1 Gordon Reid.
Replacements: 16 Dougie Hall, 17 Ryan Grant, 18 Ed Kalman, 19 Tim Swinson, 20 Rob Harley, 21 Niko Matawalu, 22 Duncan Weir, 23 Sean Lamont.
Referee: George Clancy (Ireland)
Assistant Referees: Neil Hennessy, Jon Mason (both Wales)
TMO: Gareth Simmonds (Wales)
Ulster v Newport Gwent Dragons
(Ravenhill - Kick-off: 19.05; 18.05 GMT)
Ulster's three game winless run in the Pro12 ended with their hard fought 22-18 victory over Leinster at the RDS on 30th March.
Ulster's nine game winning run against Welsh regions at Ravenhill ended with their 12-16 defeat there to Ospreys on 8th February.
Newport Gwent Dragons have slipped to three successive PRO12 losses since their 14-13 victory over Zebre in Parma in round 16.
Dragons have been victorious only once in their last nine contests against Irish provinces.
The Men from Gwent have beaten Ulster just once in their last half a dozen encounters: 22-9 at Rodney Parade in September 2011. The Dragons most recent victory at Ravenhill was in September 2008.
Ulster: 15 Peter Nelson, 14 Tommy Bowe, 13 Darren Cave, 12 Stuart Olding, 11 Craig Gilroy, 10 Ruan Pienaar, 9 Paul Marshall, 8 Nick Williams, 7 Mike McComish, 6 Robbie Diack, 5 Dan Tuohy, 4 Iain Henderson, 3 Ricky Lutton, 2 Rory Best (captain), 1 Tom Court.
Replacements: 16 Rob Herring, 17 Callum Black, 18 Declan Fitzpatrick, 19 Lewis Stevenson, 20 Ali Birch, 21 Niall O'Connor, 22 Mike Allen, 23 Adam D'Arcy.
Dragons: 15 Tom Prydie, 14 Will Harries, 13 Pat Leach, 12 Jack Dixon, 11 Ross Wardle, 10 Dan Evans, 9 Jonathan Evans, 8 Toby Faletau, 7 Darren Waters, 6 Dan Lydiate, 5 Rob Sidoli, 4 Andrew Coombs (captain), 3 Nathan Buck, 2 Sam Parry, 1 Aaron Coundley.
Replacements: 16 Hugh Gustafson, 17 Nathan Williams, 18 Dan Way, 19 Adam Jones, 20 Jevon Groves, 21 Wayne Evans, 22 Steffan Jones, 23 Andy Tuilagi.
Referee: Leighton Hodges (Wales)
Assistant Referees: Paul Haycock, Gary Conway (both Ireland)
TMO: Peter Ferguson (Ireland)
Edinburgh v Connacht
(Murrayfield - Kick-off: 19.30; 18.30 GMT)
Edinburgh have won their last two Pro12 matches against Ulster and Zebre, but have not won three in a row in the competition since October 2010.
Connacht's three game winning run in the PRO12 ended with their 0-22 reversal to Munster in cork on 23rd March.
Connacht's only victory in their last six encounters with Scottish opponents was 26-13 over Edinburgh in Galway in February 2012.
Edinburgh beat Connacht 24-23 at the Sportsground in round 10, and have not achieved a season's double over the Irishmen since 2008/09.
Connacht's only victory in eight previous visits to Murrayfield was 16-13 in March 2005.
Edinburgh: 15 Greig Tonks 14 Lee Jones, 13 Matt Scott, 12 Ben Atiga, 11 Tim Visser, 10 Piers Francis, 9 Greig Laidlaw (captain), 8 Netani Talei, 7 Hamish Watson, 6 Stuart McInally, 5 Sean Cox, 4 Grant Gilchrist, 3 Geoff Cross, 2 Ross Ford, 1 Allan Jacobsen.
Replacements: 16 Steve Lawrie, 17 Robin Hislo, 18 John Yapp, 19 Perry Parke, 20 Robert McAlpine, 21 Sean Kennedy, 22 Harry Leonard, 23 Tom Brown.
Connacht: 15 Robbie Henshaw, 14 Danie Poolman, 13 Eoin Griffin, 12 Brian Murphy, 11 Gavin Duffy (captain), 10 Dan Parks, 9 Kieran Marmion, 8 George Naoupu, 7 John Muldoon, 6 Mick Kearney, 5 Mike McCarthy, 4 Michael Swift, 3 Ronan Loughney, 2 Adrian Flavin, 1 Brett Wilkinson.
Replacements: 16 Ethienne Reynecke, 17 Rodney Ah You, 18 JP Cooney, 19 Andrew Browne, 20 Mata Fifita, 21 Paul O'Donohoe, 22 Miah Nikora, 23 Fetu'u Vainikolo.
Referee: Rhys Thomas (Wales)
Assistant Referees: Peter Allan, TBC (both Scotland)
Saturday, April 13
Cardiff Blues v Zebre
(Cardiff Arms Park - Kick-off: 14.30; 13.30 GMT)
Cardiff Blues have slipped to four successive Pro12 reversals and have not lost five in a row in the competition in the same season since 2004/05.
The Blues suffered their first ever loss to an Italian opponent when they visited Treviso in round 18.
Zebre are still looking for that elusive first win in the Pro12, but are getting ever closer having claimed three losing bonus points in their last four games.
Cardiff Blues won 14-7 when the two sides met in Italy in round 9.
Cardiff Blues: 15 Leigh Halfpenny, 14 Owen Williams, 13 Gavin Evans (captain), 12 Jamie Roberts, 11 Harry Robinson, 10 Rhys Patchell, 9 Lewis Jones, 8 Robin Copeland, 7 Sam Warburton, 6 Michael Paterson, 5 Filo Paulo, 4 Lou Reed, 3 Scott Andrews, 2 Marc Breeze, 1 Taufa'ao Filise.
Replacements: 16 Kristian Dacey, 17 Thomas Davies, 18 Benoit Bourrust, 19 James Down, 20 Luke Hamilton, 21 Alex Walker, 22 Ceri Sweeney, 23 Gareth Davies.
Zebre: 15 Ruggero Trevisan, 14 Leonardo Sarto, 13 Giovanbattista Venditti, 12 Gonzalo Garcia, 11 Sinoti Sinoti, 10 Daniel Halangahu, 9 Alberto Chillon, 8 Andries van Schalkwyk, 7 Filippo Ferrarini, 6 Josh Sole, 5 Marco Bortolami (captain), 4 Michael van Vuren, 3 Luciano Leibson, 2 Davide Giazzon, 1 Matias Aguero.
Replacements: 16 Carlo Festuccia, 17 Andrea de Marchi, 18 Salvatore Perugini, 19 Nicola Belardo, 20 Filippo Cristiano, 21 Tito Tebaldi, 22 Alberto Chiesi, 23 Matteo Pratichetti.
Referee: Lloyd Linton (Scotland)
Assistant Referees: Tim Hayes, Julian Smith (both Wales)
Munster v Leinster
(Thomond Park - Kick-off: 18.30; 17.30 GMT)
Munster's victory over English champions Harlequins last weekend saw them become the Pro12's solo representative in the last four of this season's European Cup.
The Munstermen's only victory in their last five PRO12 encounters was 22-0 over Connacht in Cork in round 18.
Munster have won their last three encounters with Irish Provinces.
Leinster's demolition of London Wasps sees them become the only non-French side left in this season's European Challenge Cup.
The Leinstermen's seven match winning run in the PRO12 came to an end with their 18-22 home defeat to Ulster in the last round.
Leinster are unbeaten away from home in 2013.
Leinster have won their last three encounters with Munster including an 18-9 victory at Thomond Park in this equivalent fixture last season.
Munster: 15 Felix Jones, 14 Denis Hurley, 13 Casey Laulala, 12 James Downey, 11 Simon Zebo, 10 Ian Keatley, 9 Conor Murray, 8 James Coughlan, 7 Tommy O'Donnell, 6 Peter O'Mahony, 5 Paul O'Connell, 4 Donncha O'Callaghan, 3 Stephen Archer, 2 Damien Varley, 1 David Kilcoyne.
Replacements: 16 Mike Sherry, 17 James Cronin, 18 BJ Botha, 19 B Holland, 20 Dave O'Callaghan, 21 Cathal Sheridan, 22 Ivan Dineen.
Leinster: 15 Rob Kearney, 14 Dave Kearney, 13 Brian O'Driscoll, 12 Gordon D'Arcy, 11 Isa Nacewa, 10 Ian Madigan, 9 Isaac Boss, 8 Jamie Heaslip, 7 Shane Jennings, 6 Sean O'Brien, 5 Quinn Roux, 4 Leo Cullen (captain), 3 Mike Ross, 2 Sean Cronin, 1 Cian Healy.
Replacements: 16 Richardt Strauss, 17 Jack McGrath, 18 Michael Bent, 19 Devin Toner, 20 Kevin McLaughlin, 21 John Cooney, 22 Andrew Goodman, 23 Andrew Conway.
Referee: Nigel Owens (Wales)
Assistant Referees: David Wilkinson, Jonathan Peak (both Ireland)
TMO: Jude Quinn (Ireland)
Ospreys v Benetton Treviso
(Liberty Stadium - Kick-off: 18.30; 17.30 GMT)
Ospreys only defeat in the Pro12 in their last ten matches since Novembers was 10-22 away to Connacht in round 15. Ospreys have won their last eight PRO12 fixtures at Liberty Stadium.
Benetton Treviso are unbeaten in their last three PRO12 encounters since losing 5-40 to Leinster at the RDS on 16th February.
Treviso have won three of their last four contests against Welsh regions in all competitions, whilst their only victory on Welsh soil since 2007 was 33-32 at the Dragons in April 2012.
The two sides have already met three times this season (once in the PRO12 and twice in Europe) with the Italian having the edge by two wins to one.
Treviso have never won on five previous visits to Liberty Stadium.
Ospreys: 15 Richard Fussell, 14 Tom Habberfield, 13 Jonathan Spratt, 12 Ashley Beck, 11 Ben John, 10 Dan Biggar, 9 Kahn Fotuali'i, 8 Joe Bearman, 7 Justin Tipuric, 6 James King, 5 Ian Evans, 4 Alun Wyn Jones (captain), 3 Adam Jones, 2 Richard Hibbard, 1 Ryan Bevington.
Replacements: 16 Scott Baldwin, 17 Duncan Jones, 18 Cai Griffiths, 19 Lloyd Peers, 20 Jonathan Thomas, 21 Rhys Webb, 22 Matthew Morgan, 23 Tom Isaacs.
Treviso: 15 Luke McLean, 14 Ludovico Nitoglia, 13 Tommaso Iannone, 12 Gideon La Grange, 11 Edoardo Gori, 10 Alberto Di Bernardo, 9 Tobias Botes, 8 Dean Budd, 7 Alessandro Zanni, 6 Simone Favaro, 5 Corniel Van Zyl, 4 Francesco Minto, 3 Lorenzo Cittadini, 2 Leonardo Ghiraldini (captain), 1 Alberto De Marchi.
Replacements: 16 Giovanni Maistri, 17 Michele Rizzo, 18 Jacobus Roux, 19 Antonio Pavanello, 20 Paul Derbyshire, 21 Marco Filippucci, 22 Fabio Semenzato, 23 Kristopher Burton.
Referee: Dudley Phillips (Ireland)
Assistant Referees: Ian Davies, Alan Jenkins (both Wales)
TMO: Tony Rowlands (Wales)