Christian Lealiifano kicked a crucial late conversion to give Ulster a dramatic 23-22 win and deny Benetton Treviso a second Pro14 victory of the season.
Before their win in Edinburgh in September, Treviso had not won on the road in the competition against a team other than Zebre since May 2013.
But they came agonisingly close to another shock result at the Kingspan Stadium, where an Andrew Trimble try two minutes from time set up Lealiifano to clinch a last-gasp triumph for Ulster.
The Italian side trailed 13-9 at half-time but rallied after the break to move into a 22-16 lead with the help of a Robert Barbieri touchdown.
However, Trimble and Lealiifano combined to deny the spirited visitors, although Leinster edged ahead of Ulster into second in Conference B thanks to a thumping 54-10 win against the Dragons.
The men from Newport moved into a 10-0 lead before conceding 54 unanswered points, Isa Nacewa scoring two of the victors' tries.
In another clash between Welsh and Irish sides, Cardiff Blues held off a late Connacht charge to win 36-30 and climb above their visitors to fourth in Conference A.
The day's early kick-off saw the Cheetahs strengthen their grip on third in Conference A with a 33-13 win against Edinburgh in Bloemfontein.