Clermont Auvergne remain top of the table, but they suffered a first defeat of the Top 14 campaign at the hands of Bordeaux.
The Southern Kings claimed a first Pro14 win of the season and consigned Glasgow Warriors to a first loss in Port Elizabeth.
Northampton Saints slumped to a third defeat in four as Bath won at The Rec, while Wasps and Bristol also secured victories.
The Cheetahs' three-match losing run in Pro14 ended but a last-gasp try saw Ulster deny them victory.
Toby Flood's yellow card proved to be costly as Exeter Chiefs made it four Premiership wins out of four.
Centre Gael Fickou has now scored three tries in two games for Stade Francais, the club he joined from Toulouse in May.
The Ricoh Arena played host to a Premiership classic on Sunday as Wasps overcame 14-man Leicester Tigers 41-35 in an eight-try thriller.
A trio of second-half scores helped Ulster to a 28-7 win at Southern Kings in the Pro14 on Sunday.
Greig Laidlaw kept his cool to maintain Clermont Auvergne's perfect start to the new Top 14 season.
Glasgow Warriors are the only club to have won each of their opening three fixtures after overcoming the Cheetahs.
Saracens needed two late tries from David Strettle to secure a come-from-behind victory over Northampton Saints.
Australia's dismal Rugby Championship continued with a rare home loss to Argentina on the Gold Coast.
New Zealand missed the chance to wrap up the Rugby Championship as South Africa earned a famous win in a Wellington thriller.
Charlie Sharples grabbed two tries as Gloucester rallied from a 10-point half-time deficit to see off local rivals Bristol Bears.
Edinburgh saw off Connacht to record their first Pro 14 win as Munster thrashed a much-changed Ospreys side on Friday.
Mathieu Bastareaud was sent off but Toulon fought back to claim their first Top 14 victory of the campaign.