John Barclay was injured while scoring Glasgow's try

Gregor Townsend was looking for a postive reaction from his player safter a string of poor performances and there certainly no lack of effort of Glasgow's part.

Castres only secured their win - their 14th successive home victory -when the visitors were reduced to 13 men with 10 minutes remaining and they scored their only try of the game through Yannick Caballero.

Glasgow still had a chance to win it but fly-half Ruaridh Jackson's penalty hit the post.

Castres move second in Pool 4 behind leaders Ulster, who they play next up in January and where the French side will be attempting to win three European Cup matches in a row for the first time since the 2001/02 season when they ended up reaching the quarter-finals.

However, they could well be without influential flanker Ibrahim Diarra, who went unpunished for a deliberate stamp on Glasgow's Moray Low, but could well be cited after the game as it was clearly caught on camera.

A dour first-half had been enlivened by Glasgow in the final minute as Ryan Wilson broke through the Castres defence and offloaded to flanker John Barclay, who forced his way over despite suffering a hamstring injury in the process, forcing him out of the game.

The Scottish side led 8-3 at the break.

Castres were equally lacklustre in the second-half, but their opponents gave them a helping hand being reduced to 13 men as the game entered its final stages as referee Andrew Small sin-binned two players, lock Tom Ryder the first to go followed a few minutes later by centre Byron McGuigan.

The hosts finally crossed the line as the Castres pack with their extra numbers dominated. Caballero touched down and with Daniel Kirkpatrick's conversion successful they took a 10-8 lead.

Glasgow fly-half Ruairidh Jackson was presented with a golden opportunity to send the visitors back into the lead with a penalty just four minutes from time but his kick came back off the post and was cleared to safety.

Gregor Townsend was left lamenting his side's inability to hold on to the advantages they have gained in Europe this term.

"We have been very competitive in every game and were 15-0 up at Northampton and we were in the game against Ulster," he said.

"We have had two close games against Castres and we need to put those nearly wins into victories.

"We expected a tough match. Castres are fourth in the French league and have an excellent home record and I think that is seven wins in a row they have put together. We knew how hard it would be but we believed in the team we had and we put them under pressure."

Warriors rang the changes for the visit to the south of France and Gregor believes there were plenty of positives to take away.

"For large parts of the game we took the game to Castres," he said.

"In the second half we struggled to get the same amount of possession from line outs. I was really proud of the players for their effort and ambition and we moved the ball really well. We looked dangerous."

Warriors paid the price for ill-discipline as Tom Ryder, who this week signed a new contract to keep him at the club until 2015, and Byron McGuigan were both sent to the sin bin before Yannick Caballero scored the match-winning try.

Gregor, who enjoyed a spell at Castres between 2000 and 2002, added: "Our scrum came under pressure, especially when we went down to 14 men. At the end of the day what killed us was two yellow cards.

"Even when we went down to 13 men I thought we put a huge effort in to protect the try line and to get that chance to win the game at the end was great. It hit the post and went out and that was the difference between winning and losing."

Gregor added: "It is up to individual responsibility and discipline. I thought on a couple of occasions in the first half we had the choice to get back and defend or go for the ball that was verging on offside.

"I believed we would improve in the second half but when you are playing away in France and the crowd really get behind their team then you have to have emotional control and we didn't in the second half."

With three big matches against Edinburgh - home and away - and Treviso to come in the next two weeks the Warriors will look for a quick recovery as they seek a play-off spot in the RaboDirect Pro12.