Saracens came racing out of the starting blocks, and with a penalty advantage in their favour after the Ospreys illegally brought down a driving maul that had rumbled forward some 25m, the ball was swung wide to Chris Wyles who went for the corner, only to be bundled into touch a couple of metres short by Richard Fussell.

From the resulting lineout, the Sarries were able to secure the ball and eventually Welsh international loosehead Rhys Gill was able to force his way over under the posts to open the scoring inside three minutes, the TMO confirming a score that was converted by Owen Farrell.

The reliable boot of Dan Biggar got the first Ospreys points five minutes later, the fly-half successfully slotting over a penalty from halfway.

Almost immediately Farrell responded in kind with a straightforward kick from in front of the posts after an Ospreys offence at the tuck.

The Ospreys then showed great composure to score their first try, from centre Ashley Beck, moving the ball from inside their own 22, Fussell, Andrew Bishop and Beck combining, the youngster going over between the sticks for his first ever Heineken Cup try.

Back came Saracens though, for their second try of a game only 15 minutes old. It came from Ernst Joubert, picking up at the base of a scrum and shrugging off the efforts of Tom Smith and Joe Bearman to score, but the talking point was the dubious forward pass decision against Fussell that led to the scrum in the first place. Farrell's successful conversion restored the home team's seven-point lead.

A great sidestepping run from Tipuric took the Ospreys back into the Saracens 22 and after Schalk Brits was pinged for offside Biggar's third successful kick cut the deficit to four.

In a game of nip-and-tuck, the next penalty went Saracens away, against Adam Jones at the scrum, but on this occasion Farrell's radar was off as he pulled it wide of the posts.

A breathless passage of play saw Saracens running it back from deep after Biggar failed to find touch with a penalty and only a last gap tackle from Bishop on David Strettle preventing the England wing scoring in the corner. The ball was moved from right to left, Saracens pounding on the Ospreys line and eventually getting a penalty, from which Farrell made no mistake.

As half-time approached the Ospreys were reduced to 14 when skipper Tom Smith was yellow carded for coming in from the side. A similar offence 60m upfield from Biggar then resulted in another Sarries kick, Farrell taking his team 10 points clear.

HALF-TIME: SARACENS 23 OSPREYS 13

A Biggar penalty after an offence by Jacques Burger at the breakdown gave the Ospreys the perfect start to the second half but again Saracens came back strongly, putting together numerous phases of play to stretch the defence before finally creating space out wide, Brits carrying well before his cheeky reverse pass freed Chris Wyles to score, Farrell off-target with his conversion attempt.

Biggar was handed the chance to cut the deficit with a seemingly straightforward penalty just to the right of the sticks but he couldn't take advantage and the Ospreys remained 12 points behind.

Back up to 15, the Ospreys were then handed a boost when Farrell was pinged for a late tackle on Biggar, resulting in him spending 10 minutes in the bin, but the Ospreys fly-half was again unsuccessful with his kick from a metre inside his own half.

A penalty against Ryan Bevington for not binding allowed Saracens to have a go at goal from long-range. Without Farrell, scrum-half Ben Spencer stepped up to try his luck but his effort never had the distance.

The Ospreys were finally able to make their numerical advantage count as the hour approached, moving the ball left from a ruck via Biggar's miss-pass, allowing Fussell to come into the line, drawing the tackle before slipping it out for Beck to score his second of the night, Biggar adding the extras to bring his team back to within five points with a little over 20 to play.

A penalty against replacement George Stowers allowed Saracens the chance to strike straight back but Farrell, newly returned to the action, was off target.

For the first time the Ospreys were starting to take control of the game, and with hymns and arias ringing out across the Wembley pitch, a great Fussell kick and chase took them deep into Saracens territory but as they looked to turn the screw, a moment of indiscipline from Ian Gough saw them back in their own half.

The Ospreys were guilty of playing themselves into trouble minutes later, Fussell getting caught as he tried to run the ball out from his own tryline, Jonathan Thomas eventually having to concede a scrum five as Saracens looked to make the game safe. After numerous resets the penalty eventually went the way of the home team, Farrell putting it over from close range to take away the Ospreys bonus point with seven minutes left.

However, it was over yet, and great work by Rhys Webb, charging down Farrell's clearance inside his 22, eventually led to an Ospreys penalty, Biggar bringing his team back to within five points.

Try as they might though, the Ospreys were unable to claw back that deficit and had to settle for the losing bonus point ahead of the return fixture at the Liberty Stadium on Friday night.