Ulster surrendered five points to a strong Saracens outfit at a wet and windy Kingspan Stadium after a 27-9 defeat.
The hosts had led 9-0 but could not score for the game's final 55 minutes while Saracens ran in three second-half scores having crossed once before the turn.
The bonus-point win came despite the Premiership champions playing 20 minutes with 14 men thanks to yellow cards for Michael Rhodes and Billy Vunipola.
With their European campaign starting on the sourest of notes, Ulster must regroup quickly to take on Leinster in the Pro12 next Friday.
Read the full match report in tomorrow's Belfast Telegraph.