Lyon's lead at the Top 14 summit was reduced to just one point as they were comprehensively beaten 33-8 by Montpellier on Saturday.
Having beaten Glasgow Warriors in the Pro14 final in May, Leinster were victorious again at Scotstoun as Cian Kelleher scored a brace.
Despite conceding 33 points, Wayne Pivac was pleased that Wales scored 43 points in his first match at the helm against Barbarians.
Northampton Saints made it four wins from five to go top of the Premiership, while Exeter Chiefs thrashed Wasps.
New Zealander Warren Gatland told the Cardiff crowd Wales has "a special place in my heart" after bidding his old team farewell on Saturday.
Wayne Pivac was victorious in his first match as Wales coach, Josh Adams and Ken Owens scoring braces against Warren Gatland's Barbarians.
In their first Premiership match since accepting a 35-point deduction for breaching salary-cap rules, Saracens defeated Bath 25-12.
Eroni Sau's try proved decisive as Edinburgh saw off Pro14 Group B leaders Munster, while Ulster thrashed Scarlets on Friday.
Warren Gatland has been honoured by Wales after his 12-year spell in charge, with an entrance to the Principality Stadium named after him.
Experienced England full-back Mike Brown will miss the rest of the Premiership season, Harlequins have confirmed.
Conor O'Shea has been announced as England's director of performance, with Nigel Melville leaving the RFU.
Having brought his 12-year stint as Wales coach to an end after the Rugby World Cup, Warren Gatland will face his former side on...
Read more
Wayne Pivac has named Justin Tipuric as captain for his first match in charge of Wales against Warren Gatland's Barbarians side.
Captain Joe Launchbury believes the future is bright for Wasps after signing a new deal.
La Rochelle's Pierre Bourgarit learned his fate on Wednesday after being sent off for eye-gouging Sale Sharks' Tom Curry.
Of all the special moments following South Africa's World Cup triumph, Siya Kolisi treasures the meeting with Jurgen Klopp.