Ulster stormed back from 10 points down to beat the Scarlets at Ravenhill and stay fourth in the Celtic League.
Ulster (10) 30
Tries: Maxwell, Howe
Pens: Steinmetz 6
Scarlets (13) 13
Pens: Davies 2
The Llanelli outfit led 13-3 thanks to a Dafydd James try, converted by Gareth Bowen, and two Barry Davies penalties.
Ulster responded just before half-time with an Andrew Maxwell try, converted by Paul Steinmetz, to be 13-10 behind.
Five Steinmetz penalties in the second half and a late try from replacement Tyrone Howe secured Ulster's win while Scarlets had Dafydd Jones sent-off.
The Welsh back row was shown a straight red card for stamping on Matt McCullough.
Former Lions winger Howe got his try minutes after coming on to win his 99th cap for the province.
"To come from 13-3 down, scoring 27 unanswered points, is a great achievement," said Ulster coach Mark McCall.
"We did not take our chances in the first half and allowed them a bit of a lead, but Maxwell's try changed the game.
"At half-time we had a lot of belief and dominated the game from then on. It was a great effort in the second half."
Ulster: Cunningham, Topping, Bell, Steinmetz, Maxwell, Larkin, Boss, J. Fitzpatrick, Brady, B. Young, Harrison, McCullough, Ferris, McMillan, Wilson.
Replacements: Shields for Brady (78), Frost for McCullough (77), N. Best for Ferris (70). Not Used: Moore, Campbell, Wallace, Howe.
Llanelli Scarlets: B. Davies, Ferry, D. James, King, G. Evans, Bowen, Stuart-Smith, Dunlea, Rees, Madden, Afeaki, Louw, D. Jones, G. Thomas, A. Popham.
Replacements: Hercus for Bowen (60), L. Davies for Stuart-Smith (60), Gravelle for Rees (68), J. Davies for G. Thomas (34). Not Used: Cooper, Quinnell, G. Evans.
Referee: P Allan (SRFU).