Indiscipline proved costly as the Ospreys fell to a fifth consecutive defeat in Glasgow, conceding 15 points during 19 second half minutes when they had players in the bin.
The Ospreys led by a single point at the break, 9-8, and following an early exchange of penalties after the restart still led going into the last half hour.
However, a disappointing final 30 saw Josh Matavesi and Ryan Bevington shown yellow cards allowing the hosts to pull away from their opponents.
Although a Dan Baker try in the 75th minute, to add to 14 points from Dan Biggar, meant that the Ospreys were in possession of a losing bonus point in the final five minutes, more indiscipline meant that Glasgow were able to take even that away from them with the final play, scoring a fourth try to secure a maximum haul.
It means the Ospreys head back to Wales tonight empty handed, with just one win to their credit from six PRO12 games, and only Treviso below them in the table after next week’s opponents Zebre moved above them yesterday courtesy of a bonus point win in Parma over Cardiff Blues.
It was Glasgow who went ahead inside 180 seconds, Duncan Weir with a simple penalty after early pressure from the hosts led to Rory Thornton bringing down the maul illegally.
Just three minutes later it was level, Biggar making no mistake from close to halfway after a Glasgow offside.
The opening exchanges were cagey to say the least, neither side able to stamp their authority on the contest but with 13 minutes on the clock Biggar’s penalty put the Ospreys in front, Sila Puafisi binding illegally at the scrum.
Despite the perfect conditions it was all very scrappy, the sound of the referee’s whistle far too prominent throughout the opening quarter, and Glasgow had the chance to level in the 23rd minute, but Weir’s long range kick drifted wide of the near post following an Ospreys offside.
Attacking opportunities were very much at premium and the first spell of concerted pressure from either side resulting in a try on the half hour, Glasgow retaking the lead through Sean Lamont.
The pressure began with a Glasgow lineout on their right, Lloyd Ashley penalised for a high tackle just inside the opposition half, allowing Weir to put his team deep inside Ospreys territory.
The defence held firm to the lineout drive, Glasgow moved it across the field and the Ospreys were able to repel several pick and drives. However, with numbers being sucked in it meant there was space available on the left and it was Leone Nakarawa whose offload found Lamont and the winger shrugged off Ben John’s attempted tackle to score.
Weir’s conversion was missed and Glasgow led 8-6. Almost immediately the Ospreys were handed the chance to retake the lead, Lee Jones penalised for not releasing, but for once Biggar’s radar wasn’t working and his kick was off target.
The fly-half was given another go just a couple of minutes later after an offside at the ruck and this time he made no mistake, splitting the posts from the 10m line to nudge the Ospreys ahead again with two minutes left in the first half.
There was still time for Glasgow to threaten before the teams headed down the tunnel, the big frame of Nakarawa prominent as the home side threatened, but solid Ospreys defence meant there was no way through and, with the clock showing time, the penalty went the visitors way, Pat MacArthur guilty of holding on.
HALF-TIME: GLASGOW 8 OSPREYS 9
The Ospreys made the worst possible start to the second half, handing Glasgow the lead through a cheap penalty, John taking out Mike Blair without the ball at the back of a ruck, Weir making no mistake with the kick from a central position 40m out.
However, the Ospreys struck straight back after Glasgow made a hash of it from the restart, the resulting scrum ending in a penalty to the Ospreys and Biggar made no mistake.
With referee Peter Fitzgibbon having earlier issued a team warning against the Ospreys for the accumulation of penalties, he eventually issued a yellow to Matavesi after one too many offences, the Fijian centre seeming mystified by the decision.
From the resulting penalty Glasgow went to the corner and although the drive was halted, the home team continued pounding the line until, eventually, it was second row Greg Peterson who stretched over to score his team’s second try of the afternoon, the score awarded after a referral upstairs to check for a knock-on. Weir converted to take Glasgow six clear with half an hour still to play.
A side entry from Scott Baldwin then allowed Weir to stretch that lead beyond a converted try.
It got worse for the Ospreys when they were reduced to 13 men, Ryan Bevington sinbinned for a pull back off the ball, his first involvement after replacing Paul James.
Glasgow maintained the pressure, making full advantage of the numerical advantage, and although the Ospreys were back up to 14 following the return of Matavesi a couple of minutes later, try number three duly arrived.
It was Alex Allen who barged his way over from a metre out despite the best efforts of replacement Alun Wyn Jones to get underneath the ball as the prop burrowed through for the score.
Weir missed the conversion, but the Ospreys trailed 26-12 by the time Bevington rejoined the action, taking them back up to 15 men.
The game was looking like petering out as we moved into the final six or seven minutes, but a rare spark behind the scrum allowed the Ospreys to attack from deep, Eli Walker carrying well up the left before replacement nine Tom Habberfield, provided the link with another man off the bench, Dan Baker, who scampered over the line to score for the second weekend running.
Biggar’s conversion brought the Ospreys back into losing bonus point territory with just five minutes to go.
However, more indiscipline was to prove costly as an offside against Dmitri Arhip with just two minutes remaining saw Weir putting the ball down into the corner as the home team looked to not only deny their opponents any consolation but to also secure a maximum five point haul.
They were duly rewarded for the decision when Taqele Naiyaravoro barged his way over from to score try number four. Weir failed with the conversion, but there was no hiding the Ospreys disappointment as the final whistle blew, the result leaving the Ospreys firmly rooted in the bottom two of the PRO12 table.
Next up for the Ospreys is a home game against Zebre at the Liberty Stadium next Saturday, kicking off at 2.30pm.