Fergus scored Glasgow's only points with a try

Glasgow had never won at the Liberty before, but going into this they were the best away side in the league this season with only three defeats on the road, and the purposeful manner with which skipper Al Kellock marched the team out in their all-white away kit showed the clear intent built up in the camp in recent weeks.

That remained visible throughout a hard-fought, stuttering game, but it was not enough in the face of the Ospreys' suffocating breakdown work.

The plans Glasgow had for Max Evans and the back three to create attacking opportunities just never materialised because the Scots never had ball for long enough, nor in the positions they needed to exert some real control on this game.

That it remained tight owed everything to their spirit and determination in defence, but though Ospreys were not at their best either, and benefited from referee George Clancy's failure to deal with their renowned rucking that regularly veers into the illegal, the Welshmen had the edge and the finish.

After a nervy opening, one slack moment and a debatable refereeing decision and Glasgow found themselves behind after nine minutes.

It was no surprise that it came from Shane Williams, the flying Wales internationalist who did for Scotland at the Millennium Stadium earlier this year. He burst out of Mark McMillan's tackle just inside the Glasgow half and raced clear of the cover after a frantic fight for the loose ball.

But television replays seemed to show that the former IRB world player of the year's boot had brushed the left touchline before he made his getaway.

The officials let it go and Biggar converted, and Glasgow's already daunting challenge quickly steepened.

The intensity and desire in both teams was clear in numerous off-the-ball skirmishes and bodies were regularly left strewn across the pitch, testament to the brutality of the collisions, and with Glasgow struggling to make any headway from the few moments they did enjoy phases of possession, it was left to Parks to try and reduce the deficit, but he fell short with a second long-range penalty with six minutes of the first half left.

Glasgow were then harshly done to again by Clancy by pulling back Graeme Morrison, when the centre finally found some space in attack with a terrific arching run. He was clear into space with two men in support attacking the final third of the field, but Clancy reacted to Ospreys' claims for crossing against Max Evans and blew for a penalty when the home players had merely been hoodwinked by Evans' dummy run.

Parks was thankful, though, that his side went into the interval just seven points down after Andrew Bishop failed to turn a charge-down of a Parks kick into a try, knocking-on near the line.

The game remained in the balance at this stage, and despite losing full-back Bernardo Stortoni to injury at half-time, the Scots were thrown a lifeline with just a minute of the second half played.

Marty Holah, the ex-All Black openside flanker, claimed a Glasgow lineout throw over the back, but threw the ball to no-one, and scrum-half Mark McMillan was on to it swiftly. He drove into the home 22 and fed Fergus Thomson who dived through tackles into the left-hand corner for Glasgow's first try.

Parks pushed the conversion across the face of the posts, but the score lifted Glasgow and the Ospreys were still making basic errors of their own.

Clancy continued to cause consternation in the visiting ranks, however, failing to penalise some blatant Ospreys infringing at rucks and then penalising Moray Low, the Glasgow prop, when he seemed in the right position to go for the ball. Biggar took advantage by converting a penalty from 40 metres with 12 minutes of the second half played.

The stand-off could not hold on to the ball minutes later after a good half-break into the Glasgow 22, yet in keeping with the fractured nature of the contest, it led to a decisive try. Clancy played advantage to Glasgow and Parks' clearance kick was collected by Williams, who ran it back, set up a ruck, for James Hook to do what Hook does best. He picked up, escaped the clutches of Kellock to attack the blind side and then deftly chipped Parks and dived on to the ball over the line for a fine solo score.

The Glasgow coaches took off Kellock and Dewey, while the home side sent on Nikki Walker, the Scotland wing, for Bishop and Filo Tiatia, another All Black, for Jones, and though there were just 12 points between the sides, and still over 20 minutes remaining, it was difficult to see how Glasgow were going to find a way back.

The Ospreys lost Jerry Collins after his head smacked into the knee of Thomson, the Glasgow hooker, and good breaks by van der Merwe and Low brought some long-awaited territory for the visitors, but they could not secure their own lineout ball, and still the Ospreys enjoyed free rein in attacking rucks from all angles.

Glasgow came more onto the ball in the final quarter, but could not find a finish to match their effort and Biggar finished off any remaining sliver of hope with a penalty in injury-time to wrap up a 20-5 win and the Ospreys place in the Grand Final, against the winners of Leinster and Munster tonight.