Dan Biggar kicked all nine points for the Welsh region in blustery conditions and saw a last-minute drop-goal effort to win the game charged down as the Ospreys’ horrid record in Scotland continued and their play-off hopes were snatched from their control.
Duncan Weir reduced the Ospreys’ lead with two successful kicks before Scotland wing Seymour pounced on a 76th minute kick-chase to seal the win.
A punishing first half in difficult conditions saw scoring chances at a premium with both defences on top and injuries breaking up play.
The Ospreys dominated territory and early possession, but were unable to find a way through the Warriors’ resolute defence which has given up just 15 tries in 17 league matches and none at home in the league since Newport Gwent Dragons ran out 23-8 winners in November.
The only score came mid-way through the first half as Biggar, with the wind behind him, comfortably slotted his first penalty after Leone Nakawara was penalised for a tackle on Rhys Webb at a ruck.
The ever influential Niko Matawalu was guilty of gifting the Ospreys an opportunity when under no pressure he knocked-on from a quick lineout in the Warriors 22.
But at the scrum the Warriors forwards came out on top as the Ospreys front row collapsed and Duncan Weir was able to clear downfield.
As with their win against Cardiff Blues a week ago, the Ospreys were at times guilty of their own downfall at the crucial moment giving up six penalties and committing four handling errors, typified when Lacey penalised them 10 metres from the Glasgow tryline for accidental offside as the Ospreys tried to manufacture a driving maul.
The restart saw a typically more resurgent Warriors side and it took just eight minutes to Weir to kick the home side level after good work by Alex Dunbar and replacement hooker Dougie Hall.
With the game breaking up, the Ospreys’ first foray into the Warriors 22 around the hour mark saw a lost lineout and after another penalty was conceded, this time on their 10-metre line, Weir kicked the Warriors ahead.
Having already lost hooker Scott Baldwin in the first half, the Ospreys lost livewire scrum-half Webb to a leg injury and it was a pivotal moment in the game with one of the visitors’ primary playmakers off the field.
A good break from the Ospreys into the Warriors 22 through Wales flanker Justin Tipuric with 15 minutes to go looked nailed on to produce a try-scoring opportunity, but the league’s top try-scorers this season struggled to find a way through and when the Warriors were found offside Biggar opted to kick from in front of the posts to level up the match at 6-6.
Both sides produced half attacks at the clock edged closer to full time and centre Hanno Dirksen led another Ospreys breakaway, but again unable to get beyond the Warriors’ final line of defence.
A run through the phases set up Biggar for a drop-goal attempt and the Wales international obliged to give his side a 9-6 lead with just eight minutes remaining.
It had been another match to forget, which has been the norm at Scotstoun in recent outings, but with everything on the line, both sides abandoned their cautious approach which produced a thrilling few minutes.
A break and cross kick forward from Matawalu left the Ospreys scrambling back and Scotland wing Seymour steamed into get the crucial downward pressure, confirmed by the TMO to the delight of the frozen home crowd. Weir’s conversion drifted into the left upright and wide to give the Warriors a two-point lead.
With two minutes to go Weir missed a penalty attempt from distance, but from the restart the Warriors were on the attack again and were unlucky not to have stretched their lead as the impressive Finn Russell went over, but the TMO adjudged Richie Vernon had knocked-on and Josh Strauss was offside.
If that wasn’t enough there was further drama to come as the Ospreys delayed a ball back to Biggar for a second drop-goal effort which was charged down by Matawalu and booted into the Ospreys 22, but the Fijian was unable to get to the ball first in the goal area.
It mattered not as the Warriors celebrated their most important win of the season.
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