Ospreys up to second with Saints win
Ospreys up to second with Saints winSHARE
Rhys Webb scored two tries and there was one apiece from Dmitri Arhip and Justin Tipuric as the Welsh region went two points ahead of Saracens, who went down 21-24 at leaders ASM Clermont Auvergne.
It was the prop Arhip who gave the hosts a blistering start, finishing off in the corner after Tom Habberfield's thrilling run.
Harry Mallinder scuppered a great chance for a quick reply with a delayed final pass and two Sam Davies penalty gave Ospreys an 11-0 lead after a rather scrappy first half.
There was hope for Saints after a difficult week when Piers Francis' cross-kick was knocked down by Ashee Tuala and Mallinder curled himself into a ball to avoid touch on his way over the line.
A Francis penalty then reduced arrears to 11-8, but Ospreys then turned up the heat, replacement Webb touching down, before a lovely move was finished off by Tipuric.
Webb grabbed his second, and the bonus point, soon afterwards. A Reece Marshall close-range try in injury time barely raised a smile from the men in green.
Ospreys' bid to reach the quarter-finals rests on a home game with Saracens in mid-January before they travell to Clermont in their final fixture. Northampton have now lost all four of their Pool 2 fixtures.
Tries: Arhip, Webb 2, Tipuric
Cons: Davies 3
Pens: Davies 2
Tries: Mallinder, Gibson
Ospreys: 15 Dan Evans, 14 Ben John, 13 Kieron Fonotia, 12 Owen Watkin, 11 Jeff Hassler; 10 Sam Davies, 9 Thomas Habberfield, 8 Olly Cracknell 7 Justin Tipuric, 6 Dan Lydiate, 5 Alun-Wyn Jones, 4 Bradley Davies, 3 Dmitri Arhip, 2 Scott Baldwin, 1 Nicky Smith.
Replacements: 16 Scott Otten, 17 Paul James, 18 Ma'afu Fia, 19 Adam Beard, 20 Rob McCusker, 21 Rhys Webb, 22 Dan Biggar, 23 Ashley Beck.
Northampton: 15 Harry Mallinder, 14 Ahsee Tuala, 13 Rob Horne, 12 Tom Stephenson, 11 Ben Foden, 10 Piers Francis, 9 Nic Groom, 8 Teimana Harrison 7 Tom Wood, 6 Jamie Gibson, 5 Michael Paterson, 4 David Ribbans, 3 Jamal Ford-Robinson, 2 Mikey Haywood, 1 Francois van Wyk.
Replacements: 16 Reece Marshall, 17 Campese Ma'afu, 18 Paul Hill, 19 Api Ratuniyarawa, 20 Lewis Ludlam, 21 Cobus Reinach, 22 Luther Burrell, 23 Ken Pisi.
Referee: Marius Mitrea (Italy)
Assistant referees: Manuel Bottino (Italy), Matteo Liperini (Italy)
TMO: Stefano Pennè (Italy)