Ulster topple the defending champions
Ulster topple the defending championsSHARE
Masterful kicking from John Cooney had put Ulster in control in a quiet first half before the game burst into life in the second phase.
Three tries in six whirlwind minutes saw the defending champions wrestle back the advantage as first John McNicholl and then Jonathan Davies went over the line after Jacob Stockdale had given Ulster a slender lead.
Christian Lealiifano's penalty levelled things up for the hosts before Andrew rounded-off a fine Ulster move with three minutes to go to seal a thrilling triumph.
It was an emotional night in Belfast after a minute's silence was held to mark the five-year anniversary since the death of promising young centre Nevin Spence, who died along with his father Noel and brother Graham, in a farming accident.
Following the moving tribute, it was the visitors that started off the brighter, quickly hitting the front through the boot of Leigh Halfpenny.
The hosts responded immediately to the setback and began to dominate the ball without breaking the Scarlets backline.
It would take until the 23rd minute for the Ulstermen to finally make an incisive breakthrough and were yards from the line but Matthew Rea was unable to keep possession after 21 phases of Ulster play.
The excellent kicking of scrum-half Cooney gave Ulster a six-point lead at the break but Les Kiss would have been left frustrated at his side's inability to get over the whitewash.
An early penalty extended the Ulstermen's lead but Scarlets finally gave themselves a lifeline with 20 minutes to play.
A breakdown in an Ulster attack gave way to a swift counter from the visitors which was finished off by McNicholl. Halfpenny's simple conversion put them in front despite long spells on the back foot.
That only spurred the home side into life as a scintillating try nudged the Ulstermen back in front.
Stuart McCloskey charged down the wing before offloading to Sean Reidy who was able to find Stockdale as he burst over the try line.
But that was far from the end of the drama as Scarlets hit back again. Ulster were left short down the wing which allowed Steff Evans to exploit the space and tee up Davies, who waltzed over the line to round off a breathtaking six minutes of rugby.
Lealiifano's penalty levelled things up to set up a tense finish but there would be a final sting in the tail as Andrew went over the whitewash with three minutes remaining.
McCloskey was able to ride a tackle on the halfway line before the ball was eventually recycled and went wide to hooker Andrew who was left with the Kingspan turf all to himself as he went over to clinch a dramatic victory.
Tries: Stockdale, Andrew
Pens: Cooney 4, Lealiifano
Tries: McNicholl, Davies
Cons: Halfpenny 2
Pens: Halfpenny 2
Ulster: 15 Louis Ludik, 14 Andrew Trimble, 13 Luke Marshall, 12 Stuart McCloskey, 11 Jacob Stockdale, 10 Christian Lealiifano, 9 John Cooney, 8 Sean Reidy, 7 Chris Henry (captain), 6 Matthew Rea, 5 Alan O'Connor, 4 Kieran Treadwell, 3 Wiehahn Herbst, 2 Rob Herring, 1 Kyle McCall.
Replacements: 16 John Andrew, 17 Andrew Warwick, 18 Rodney Ah You, 19 Robbie Diack, 20 Clive Ross, 21 Paul Marshall, 22 Peter Nelson, 23 Tommy Bowe.
Scarlets: 15 Leigh Halfpenny, 14 Johnny McNicholl, 13 Hadleigh Parkes, 12 Scott Williams, 11 Steff Evans, 10 Rhys Patchell, 9 Gareth Davies, 8 John Barclay, 7 Will Boyde, 6 Aaron Shingler, 5 Tadhg Beirne, 4 Jake Ball, 3 Samson Lee, 2 Ken Owens (captain), 1 Rob Evans.
Replacements: 16 Ryan Elias, 17 Wyn Jones, 18 Werner Kruger, 19 David Bulbring, 20 Josh Macleod, 21 Jonathan Evans, 22 Rhys Jones, 23 Jonathan Davies.
Referee: Marius Mitrea (Italy)
Assistant referees: Vincenzo Schipani (Italy), Kieran Barry (Ireland)
TMO: Alan Falzone (Italy)