Worcester Warriors were unable to complete a comeback from 18-0 down at Sale Sharks as they remain winless in the Premiership.
Clermont won an early top-of-the-table clash with Stade Francais, while there were also Top 14 victories for Racing 92, Toulouse and Lyon.
Pro14 champions Leinster were defeated by last season's runners-up Scarlets in a tense clash on Saturday.
Danny Cipriani inspired Gloucester's comeback as a former Bath player denied the hosts victory at the Rec on Saturday.
Michael Cheika gained some much-needed respite as he watched his Australia side beat South Africa 23-18 in the Rugby Championship.
Though New Zealand ran out 46-24 winners over Argentina, the All Blacks' victory was far from a convincing one.
John Cooney kicked a last-gasp penalty for the second successive week as Ulster left it late to beat Pro14 rivals Edinburgh.
Dan Biggar kicked 17 points and Dylan Hartley came off the bench to score a try as Northampton Saints edged out Harlequins.
Clermont Auvergne made the most of a chaotic spell in which Racing 92 were reduced to 13 men, triumphing in Top 14 on Sunday.
Alex Lewington and Owen Farrell helped Saracens to a handy away win at Newcastle Falcons on Sunday.
Castres overturned a 13-point deficit in the second half to beat Lyon in Saturday's Top 14 action.
John Cooney's kicking got Ulster up and running, while Connacht's Craig Ronaldson fell just short and Munster ran riot in Pro14.
Danny Cipriani produced a sensational pass for Charlie Sharples' try while Billy Twelvetrees kicked 17 points in Gloucester's victory.
Bryan Byrne's late try and Ross Byrne's subsequent conversion saw champions Leinster snatch victory over Cardiff Blues in the Pro14.
The opening game of the 2018-19 Premiership season saw newly promoted Bristol Bears defeat Bath 17-10 in a lively west-country derby.
Montpellier failed to exact revenge on Castres in a repeat of the Top 14 final, losing their first game of the season at Altrad...
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