Munster ground out a hard-fought 10-3 victory over the Stormers at a drenched Thomond Park after academy lock Edwing Edogbo's second try in five.
Fly-half JJ Hanrahan's second-half penalty edged Connacht to an outstanding 13-12 United Rugby Championship victory over the Sharks in Durban.
Ulster came from behind to beat the Lions 24-17 at a windswept Kingspan Stadium scoring three tries to the visitors' two in game which was in the balance throughout.
Edinburgh claimed a fourth victory from five starts in the United Rugby Championship (URC) when they battled to a 31-23 victory against the Bulls at Hive Stadium.
The Lions face Irish outfit Ulster for their final tour match in Round 5 of the United Rugby Championship. Kick-off is at 21:35 on Friday evening at Kingspan Stadium.
The Bulls focus on Edinburgh as the league leaders look to complete their European travels with another successful showing in the United Rugby Championship.