Ulster survived having Rodney Ah You sent off late in their match at Newport Gwent Dragons to win 27-17 and stay ahead of Scarlets in the Pro12.
Ah You saw red for a shoulder barge with four minutes to go at Rodney Parade, where John Andrew powered over from a maul three minutes later to make sure of the result for the visitors, Paddy Jackson converting.
With direct rivals Scarlets also winning on Friday, the victory keeps Ulster fourth, inside the play-off spots and three points clear of the fifth-placed Welsh team.
Craig Gilroy was the man to make Ulster's dominance in the first half count, touching down after seizing on a kick-through from Ruan Pienaar, who added the extras, before Angus O'Brien's penalty reduced the deficit to four points.
Gilroy was harshly sent to the sinbin after being deemed guilty of an intentional knock-on early in the second half and Newport took full advantage, Rynard Landman crossing following a lineout drive and O'Brien converting to level the scores at 10-10 in the 50th minute.
Ulster quickly reasserted themselves, going through the phases before Jared Payne got over, the TMO giving the try the all clear after queries over potential obstruction. Pienaar sent over the additional points before departing for a Head Injury Assessment after being caught by a stray boot.
Newport refused to lie down, though, Ollie Griffiths charging down an attempted clearance to score, O'Brien again doing the business with the boot to make it 17-17 with 13 minutes to go.
But more late Ulster pressure eventually told, Jackson kicking the visitors back in front with a penalty in the 74th minute, before a dramatic conclusion saw Ah You given his marching orders and Andrew cap off the win.
Scarlets defeated Edinburgh 26-10 thanks to the returning Rhys Patchell's brace of tries, as well as singles from Wyn Jones and James Davies, with Phil Burleigh replying for the visitors after charging down Aled Davies' attempted clearance.
Patchell, making his first appearance since January 1 after recovering from a knee injury, announced his comeback with a brilliant solo effort just three minutes in before later collecting Hadleigh Parkes' high pass to cross again.
He also converted three of Scarlets' four tries in the opening 40 minutes to put his team firmly in charge before departing early in the second period.
And that key contribution proved to be decisive, as a limp second period ended scoreless.