Danny Grewcock was Bath's destroyer in chief as Glasgow's Heineken Cup dreams were shattered at frosty Firhill.

The giant lock marked his return to the line-up with a commanding display, along with a remarkable solo try, to give his side a golden chance of earning the tag of top seeds in the quarter-finals.

Warriors survived a shaky first half to reach the interval just seven points in arrears, but Grewcock struck in lethal style seconds after the restart.

Glasgow had made a rip-roaring start, testing the Bath backline defence with a series of potent surges and they edged in front with a 22-metre penalty from Dan Parks after the visitors were lured offside.

Bath replied in positive fashion as the home pack struggled to combat the first rolling maul. They kept up the momentum and squared the score through the trusty boot of Olly Barkley, also for an offside verdict in midfield.

The west country outfit set up the opening try opportunity by forcing lock Tim Barker to carry the ball into touch close to the corner flag.

It was no surprise when Bath again used the maul ploy, but Glasgow enjoyed a reprieve when Irish referee George Clancy whistled for obstruction just a metre from the target, giving Parks the chance to clear the immediate danger.

Centre Andy Henderson found a gap to send a wave of anticipation through the home support, only for the ball to squirm from his grasp as he tried to offload to his support runners.

There was another let-off for the Warriors midway through the half when Barkley sent a long-range penalty wide after Johnny Beattie was warned for backchat.

Parks put Glasgow on the offensive with a huge clearance from his own 22, but the initiative was lost as Bath earned another penalty for a line-out offence.

Bath stand-off Chris Malone then squandered a clear-cut opportunity to put the visitors back in front when his drop-goal bid was miscued from dead in front of the posts.

They began to assert their physical power in the build up to the interval, spurning two pots at the posts in favour of attempts to grab seven points. And to add to Glasgow's worries, Barker was sent to the sin-bin for a professional foul.

From the fourth penalty in quick succession, they achieved the breakthrough with scrum-half Nick Walshe darting through for the touchdown. Barkley found his touch to slot the tricky conversion.

The Warriors were dealt another blow two minutes later as flanker Steve Swindall left the action with a hip problem and was replaced by Gregor Hayter.

Grewcock then stunned Glasgow with a solo effort just two minutes after the restart. The home midfield defence was absent as the Lions giant galloped through under the crossbar to give Barkley a formality of a kick.

But the Warriors refused to buckle and they instantly blasted their way back into the contest. Parks caught the Bath markers on the hop with a quick tapped penalty, Barker provided the link and prop Kevin Tkachuk bullocked over.

Parks converted to restore the seven-point gap.

The revival was halted as Bath carved out their third try on the hour. Substitute centre Andy Craig allowed Barkley to dash down the middle before setting Tom Cheeseman free to cruise 20 metres to the line. Barkley followed up to add the extras from wide on the right.

Glasgow piled on the pressure in the frantic closing stages, but a combination of spilled passes and stout defence by Bath staved off any meaningful fightback.

And the clinical finishing skills of the visitors was underlined when full-back Mike Stephenson collected the bonus point score, goaled by Barkley.