Connacht 3 Ospreys 19:Tommy Bowe struck for the only try of the game as the Ospreys ended Connacht's proud record of having won their opening league match every year since the competition began in 2001.
It was a positive start for new Ospreys coach Sean Holley as the Welsh region won away from home in the Magners League for the first time since the 2006/07 season.
In driving wind and rain at the Sportsground, the visitors played the conditions smartly and turned around with a 13-0 interval lead.
Connacht, with four new recruits in their line-up including half-backs Ian Keatley and Frank Murphy, struggled as they faced into the wind in the opening half.
Continuing his solid pre-season form, Ospreys number 10 James Hook directed play early on although he was successful with only one of his first three penalty attempts for a fourth-minute lead.
His radar right on target again in the 19th minute when his beautifully weighted chip kick set up the try for Bowe on his Ospreys debut after leaving Ulster in the off season.
With the conversion added, the Ospreys moved 10-0 ahead and Connacht's night darkened further when their new captain John Muldoon was sin-binned, near the half-hour mark. Hook banged over the resulting penalty.
Michael Bradley's side, with the elements at their backs, made a morale-boosting start to the second half as Keatley potted a penalty goal after Ospreys hooker Huw Bennett saw yellow.
However, with 13 full internationals in their starting line-up, the Ospreys had more than enough experience to see out the result.