Scotland scrum-half Chris Cusiter made a winning return from a shoulder injury as Glasgow beat Exeter Chiefs 29-26 at Sandy Park.
Cusiter, who has been sidelined for a year, came on as a replacement and played for half an hour as the Warriors outscored their hosts four tries to two.
At the Rec, Bath also scored four tries in their 27-10 victory over the Ospreys with new fly-half George Ford leading the charge with two conversions and a penalty.
Gloucester got the better of the Scarlets in another Anglo-Welsh clash at Kingsholm, winning 31-17, with James Simpson-Daniel, Billy Twelvetrees, Matt Kvesic and Rob Cook all scoring tries.
At Donnybrook, PRO12 champions Leinster suffered a 21-13 defeat to Northampton with a 50th minute try from Saints second-rower Sanu Manoa proving to be the difference between the sides.
Premiership champions Leicester beat Ulster 30-10 at Welford Road in a game which was overshadowed by the head injury sustained by Leicester's fly-half Toby Flood.
Saracens scored ten tries in their 71-12 triumph over Bedford Blues with young New Zealand wing Jack Wilson scoring a brace of tries.
Munster wing Ronan O'Mahony was the Irish province's hero, scoring a hat-trick of tries in their 27-13 victory over London Irish at Musgrave Park.
Premiership newbies Newcastle Falcons suffered their first defeat of the pre-season, going down 15-5 to Edinburgh in Hawick. For Edinburgh, Greig Laidlaw (3) and Piers Francis (2) kicked penalties and Newcastle's only points came via a Phil Godman try.