Stefan Terblanche was the Ospreys' hero as he grabbed a superb long-range try before landing the winning drop goal to knock Bath out of the EDF Energy Cup...
The former Springbok full-back ran virtually the full-length of the pitch for his second-half try which swung the game the Ospreys way.
And his drop goal ten minutes from time put the Welsh region back into the lead before Wales fly-half James Hook put the nail in Bath's coffin with a late drop goal which sealed the win.
Having blasted Gloucester off the park 49-19 last weekend in the Anglo-Welsh competition, the Ospreys came down to Bath having made 11 changes with most of their stars rested.
New Zealander Jason Spice took over from ex-All Black Justin Marshall at scrum-half and Henson's place in the No 10 shirt was taken by Shaun Connor.
Bath scrum-half Nick Walshe landed an early penalty, but the Welsh region hammered their hosts' line before Connor's long pass gave wing Jonny Vaughton space to touch down out wide.
Connor missed the conversion and although Walshe nosed his side 6-5 ahead, the Ospreys were soon back on top.
A towering up-and-under from Spice was tapped back by flanker Steve Tandy into the grateful arms of James Hook who sprinted away from the covering defence and dotted down out wide.
Connor nailed the conversion from near the touchline and banged over a drop goal from 40 yards out as the guests breezed out to a 15-6 lead with 30 minutes gone.
Henson's understudy showed he can work his own magic by slotting over a penalty again from 40 yards out.
It was all one-way Ospreys traffic until Spice was shown the yellow card under the shadow of his own posts for deliberately kicking the ball away at a ruck.
From the resulting penalty, Walshe landed the penalty to make it 18-9 at the break.
Bath came back with a vengeance after the break and camped on the Ospreys line.
Referee Dave Pearson handed out a final warning before spotting Ian Evans holding down at the line-out and showed him a yellow card.
Walshe landed the resulting penalty and Bath were back in the game at 18-12 with 50 minutes gone.
Wales forward Alun Wyn Jones joined the fray and had an immediate impact when he won a turn over near his own line and prop Andrew Millward charged away from his own line.
He flicked a pass out to Terblanche and the flying full-back pinned back his ears.
His opposite number Nick Abendanon(CORR) closed him down, but Terblanche simply stepped inside him to touch down.
Connor kicked the conversion and the Ospreys moved into a 25-12 lead despite being a man down.
The home side rallied with two tries in as many minutes to centre Tom Cheeseman who dived under the posts for a converted try before crossing out wide less.
Walshe missed the second tricky conversion from out wide narrowing the scores to 25-24 going into the games final stages.
The Welsh region battered the Bath line until Terblanche coolly stuck the winning kick, although referee Pearson missed it and had to consult the video ref to validate the score.
But there was no mistake five minutes later when Hook slotted over his side's third drop goal to make the win safe.
Bath: Cheeseman (2) tries; Walshe con; Walshe (4) pen
Ospreys: Vaughton, Hook, Terblanche tries; Connor (2) con; Connor pen; Connor, Terblanche, Hook drop-goals
Yellow-card: Spice 33, Evans 45
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