Defending champions Leinster struggled past debutants Exeter in a scrappy 9-6 victory in their European Cup opener on Saturday.
Leinster, the champions in 2008-2009, 2010-2011 and last season, were forced to grind their way to victory, with Ireland international flyhalf Jonathan Sexton kicking three penalties.
Sexton put Leinster ahead in the 11th minute after former Ulster center Ian Whitten was penalized for playing an opponent in the air, but the expected avalanche of points never materialized and Exeter drew level on the stroke of halftime when Gareth Steenson succeeded with a penalty after two earlier misses.
Sexton put the champions back in front after 53 minutes, but Steenson again pulled Exeter level 12 minutes later when Leinster were penalized for slowing the ball down at a ruck inside their own 22.
Exeter replacement prop Ben Moon was then punished for straying offside in the 74th minute and Sexton gobbled up the opportunity with the decisive penalty in front of the posts.
Exeter had a chance to level in the last minute, but Ignacio Mieres went well wide with an optimistic 48m penalty attempt.
“It was no surprise to us how tough they were to break down. They are a formidable side,” Leinster coach Joe Schmidt said. “They are greater than the sum of their parts, well coached, well organized and hard to break down.”
In the day’s other Pool 5 game, ASM Clermont Auvergne came back from 13-6 down to trounce Llanelli Scarlets 49-16 in France, running in six tries for a crucial bonus point.
Jonathan Davies gave the Welsh visitors a third-minute lead, but it proved to be their only try as Sitiveni Sivivatu, Lee Byrne, Damien Chouly, Julien Bonnaire and Napolini Vonowale-Nalaga all crossed for Clermont, with a penalty try also awarded.
Harlequins routed Biarritz 40-13 in a four-try bonus-point performance.
England scrumhalf Danny Care scored the opening try, before Arnaud Heguy helped the French draw level 13-13 at the interval, but ’Quins ran riot in the second half with tries from Rob Buchanan, Jordan Turner-Hall and Seb Steggman.
“The players were so positive at halftime and that was good. We kept on trying to play and we knew the scores would come,” ’Quins director of rugby Conor O’Shea said.
In the other Pool 3 game, Connacht saw off Italian club Zebre 19-10.
Olly Barkley turned in a masterful performance on his debut for Racing-Metro, overseeing a 22-17 victory over former two-time champions Munster in Pool 1.
“You don’t win games like that, against teams like Munster, without a really good team spirit,” Barkley said.
The Irish scored the game’s opening try after 15 minutes when flanker Sean Dougall bounced off a couple of weak tackles to crash over from short range, with Ronan O’Gara adding the extras.
Against the run of play, Racing scrumhalf Maxime Machenaud touched down for a try that Barkley converted to draw the scores level.
Barkley was successful with two more penalties either side of the break, before Munster wing Simon Zebo outpaced Mirco Bergamasco to score a memorable converted try.
Barkley handed the home side the lead once again late in the game, before Bergamasco stretched that further with a late penalty.
Last season’s semi-finalists Edinburgh suffered a humiliating 45-0 home drubbing at the hands of Saracens.
The English side scored tries through Sam Tomkins, Owen Farrell, Chris Ashton, Alex Goode and Charlie Hodgson, the flyhalf also scoring four penalties and four conversions.