Rob Baxter's Exeter Chiefs survived a late scare to defeat Sale Sharks and remain firmly on track for the Champions Cup quarter-finals.
Toulouse have hit form and made light work of Bayonne at home, while Brive defeated Stade Francais.
Ospreys were no match for Saracens on Saturday, while Exeter Chiefs were among the other European Champions Cup winners.
Scrum-half Joe Simpson scored two first-half tries but Gloucester could not contain Toulouse after the break at Kingsholm.
An early red card was decisive as Bordeaux-Begles suffered their second defeat of the Top 14 season.
It was another game and another win for Lyon in Top 14, where Castres were defeated by Toulouse on Saturday.
Despite seeing their try line breached for the first time this season, Lyon maintained a 100 per cent start to the season in the Top 14.
The top two in the Top 14 claimed huge victories to stay unbeaten as both the defending champions and last year's runners-up were beaten.
Clermont Auvergne suffered a derby defeat to Top 14 new boys Brive as defending champions Toulouse earned their first win of the season.
Toulouse won the Top 14 last season but they have been beaten in each of their first two matches at the start of the 2019-20 campaign.