Ulster maintained their 100 percent Guinness PRO14 record and went top of Conference B after becoming the first side to defeat defending champions the Scarlets in a dramatic finish.

Sub John Andrew's 76th minute try secured a 27-20 victory for the home side at the Kingspan Stadium after the lead had changed hands several times in the second half.

Jacob Stockdale crossed the Scarlets' line after 63 minutes, while the visitors' tryscorers were Johnny McNicholl and returning Lion Jonathan Davies.

John Cooney kicked four penalties while Christian Leali'ifano kicked a penalty and the conversion of Andrew's late try.

The game got underway after a minute's applause, followed by a silence, just before kick-off on the fifth anniversary of the death of former Ulster player Nevin Spence.

All three of the visitors' Lions were in the squad -- and they were ahead after just three minutes through a Leigh Halfpenny penalty.

That was evened out in the 18th minute when Cooney landed Ulster's first points from the tee after a line-out infringement from the visitors.

He then nudged them ahead in the 31st minute after Ulster had laid siege to the Scarlets' line, nearly getting over from a maul.

Cooney's third penalty quickly followed a minute later to put the home side 9-3 up -- and that is how a scrappy first half ended.

Cooney kicked another penalty in the 52nd minute to put Ulster further in front, although it was the Scarlets who hit back next with Halfpenny landing a close-range penalty after Stuart McCloskey had strayed offside.

The Scarlets then broke out of their half on a rare sortie which saw Rhys Patchell put McNicholl through to dot down on 61 minutes -- and Halfpenny's conversion put them ahead for the first time since early in the first half.

Ulster were quick to respond with Sean Reidy bursting through and putting Stockdale in the corner, although Cooney failed to add the difficult extras.

But, with the game really opening up, Steff Evans supplied sub Davies with a great score worked down Ulster's right flank. Halfpenny converted and the Scarlets led 20-17.

With Cooney taken off, Leali'ifano levelled the scores with a penalty on 72 minutes.

Then with four minutes remaining a marvellous Tommy Bowe break saw Luke Marshall spin out a long pass for sub Andrew to gallop over - and Leali'ifano added the conversion.