Connacht stunned the Pro 14 champions at the RDS with a 35-24 victory, marking their first win in Dublin since 2002.
The away side had the brighter start as out half Jack Carty scored an intercept try.
Carty scored again after 22 minutes when he touched down close to the line. Scott Penny got the home side back in it when he picked up the ball quickly from the ruck and touched down.
Johnny Sexton went off early in the game after a HIA, which meant winger Jimmy O'Brien had to play as out half.
Alex Wooton scored just before half time for Connacht to make the lead at the break 25-5.
HT| We go into the break leading 25-5.
🔵5-25🟢#LEIvCON #GuinnessPRO14 pic.twitter.com/y3qLACmkPYAdvertisement— Connacht Rugby (@connachtrugby) January 2, 2021
Leinster hit back straight away in the second half with a try from Luke McGrath who made the score 12-25.
After a raft of changes from the home side, substitute Sean Cronin peeled away from a maul and sent through Ryan Baird for the score.
Leinster trailed 17-28 going into the final quarter of the second half, but had a try chalked off for obstruction.
The game was effectively ended when Tom Daly intercepted a Leinster pass once again to make the score 17-33.
A late Leinster try made the scoreboard looked slightly better for the home side, but it was too little to late.
We’ve done it! After a brilliant performance we come away from the RDS as 35-24 victors over Leinster.
🔵24-35🟢#LEIvCON #GuinnessPRO14 pic.twitter.com/SCDY0titpA— Connacht Rugby (@connachtrugby) January 2, 2021
Earlier in the day, it was 10 wins from 10 for Ulster in this season's Guinness PRO14 after they beat Munster at the Kingspan.
First-half tries from Ethan McIlroy and Matt Faddes helped the Conference A leaders defeat Munster 15-10 in Belfast.
𝙁𝙐𝙇𝙇-𝙏𝙄𝙈𝙀
Ulster make it 10 from 10 in the @PRO14Official! #ULSvMUN #GuinnessPRO14 #SUFTUMLive ⚪️🔴 pic.twitter.com/4aGMhn9khD— Ulster Rugby (@UlsterRugby) January 2, 2021