Simon Zebo scored a second-half try for Racing 92 but couldn't prevent them falling to defeat at home to Lyon, who triumphed 19-13 in large part thanks to the boot of Lionel Beauxis.
Racing's third defeat of the season leaves them lying in seventh position after seven games with Lyon up to third.
Perpignan's miserable start to the season continued as Paddy Jackson nailed all three of his penalty goals but still saw his side slump to a seventh defeat on the trot in a 12-9 defeat away to Pau.
Sean Dougall and Paddy Butler both started in the back row for the victors who triumphed by virtue of Antoine Hastoy's kick with over 82 minutes on the clock.
Stade Francais' impressive opening to the season continued with a 14-9 win away to fifth-placed Castres.
Stade, for whom Paul O'Connell is forwards coach, held off Castres with Julian Arias's try early in the second half proving pivotal.
Gareth Steenson shone as Exeter Chiefs came from behind to beat Bath in a thrilling 39-24 victory at the Recreation Ground.
The Dungannon born out-half kicked 14 points (four conversions and two penalties) as he led the 2016-17 Premiership champions to a sixth successive victory. They are joint top of the table with Saracens and nudging ahead on points difference.
Ian Madigan kicked a solitary conversion as Bristol Bears were battered sideways in Sixways Stadium. Pat Lam's team shipped seven tries against the Worcester Warriors in a 52-7 defeat.
Geordan Murphy's Leicester Tigers, after a patchy start to the season, claimed a vital 23-15 win away to Northampton with the boot of George Ford proving pivotal alongside tries from Ben Youngs and Jordan Olowofela. Northampton outscored the visitors in the try stakes but didn't split the posts once via conversion, penalty or drop goal.
Bernard Jackman's Dragons, bolstered by wins against the Southern Kings and Zebre last month, couldn't add to their W column this weekend as they fell to a 23-15 defeat at home to rivals Cardiff Blues.
It looked so promising for Jackman's side. They led 12-0 after a half hour. Owen Lane got the visitors back in to the game before the break but Jordan Williams penalty on the hour mark gave Dragons a 15-11 lead as they entered the closing stages.
From there, they imploded with tries from Kristian Dacey and another from Lane condemning them to another defeat.
Allen Clarke's Ospreys team gave an encouraging display but were narrowly pipped by last year's finalists Scarlets away from home.
George North's try on 33 minutes put the visitors ahead but the boot of Leigh Halfpenny combined with Rhys Patchell's try just before the hour enabled the 2017 champions to get over the line.