Second half tries from Garry Ringrose and Sean Cronin did the damage for Leinster in their 20-3 Guinness PRO14 derby win over 14-man Connacht at the Sportsground.

Jonathan Sexton ended a bruising first half with successive penalties, handing Leinster a 6-3 lead with the wind advantage to come. Sean O’Brien had an earlier-than-expected entrance in the 25th minute, returning from his shoulder operation in April to replace the injured Rhys Ruddock.

Keen to banish memories of a stinging 47-10 defeat on their last trip to Galway, Leo Cullen’s men seized control with Ringrose’s sparkling solo effort just 43 seconds into the second period and Cronin’s seven-pointer approaching the hour mark.

Jack Carty’s second-minute penalty stood as Connacht’s lone score, and the sending-off of their replacement prop Dominic Robertson-McCoy for a stamp to Josh van der Flier’s head sealed their fate with 11 minutes remaining.

Carty’s early place-kick rewarded Australian flanker Colby Fainga’a for his breakdown work, but a lost restart had the hosts scrambling and Luke McGrath’s fumble of a Jack Conan pass saw Leinster blow the game’s first try-scoring chance.

Pressure was absorbed by both defences, Connacht winning a turnover from a dangerous Leinster maul and then James Lowe, having bounced off Tiernan O’Halloran’s attempted tackle, threw a loose delivery back inside. A second surge by winger Lowe, this time infield, was spoiled by a rushed pass to his support.

Sexton opened Leinster’s account six minutes before the break, with Scott Fardy muscling through after a grounded maul. Connacht were caught offside in midfield and the visitors’ captain duly levelled. Man-of-the-match van der Flier was held up by Bundee Aki under the posts before Sexton booted fast-finishing Leinster ahead with a penalty from straight in front.

The defending champions pushed 13-3 clear on the resumption as Ringrose probed close to the Connacht 22-metre line, jinking inside before brilliantly zooming through a gap between Quinn Roux and Connacht’s own Sean O’Brien to score and stun the home side. Sexton added the extras from close range.

Connacht continued to fall foul of referee John Lacey’s whistle, allowing the Leinster pack to dictate and a close-in 55th-minute maul saw hooker Cronin scramble over from five metres out. Sexton nailed his most difficult kick of the night to open up a 17-point lead, which Jordan Larmour went close to adding to from his own chip through.

Leinster’s suffocating defence – led by van der Flier – continued to give very little away, as exemplified by replacement Andrew Porter’s penalty win at the breakdown which put an end to a prolonged spell of attacking from Connacht.

After Robertson-McCoy saw red for ‘a clear stamp to the head’ according to Lacey, who deliberated with TMO Simon McDowell, the visitors missed out a late try when replacement Rory O’Loughlin was thwarted by his own knock-on near the try-line.