Gregor Townsend, the Glasgow Warriors head coach, believes that Carlin Isles, the USA sevens wing billed as "the fastest man in rugby" could become the Warriors' X Factor player when he joins the Scotstoun side in two weeks' time.

Isles' raw pace - he can cover 100 metres in 10.3 seconds - is not in doubt, but he is still a relative novice in many aspects of rugby. However, Townsend has faith the 24-year-old American will be as quick to learn the game as he is when playing it, and that he will have a positive influence on the wider Warriors' culture.

"I think it's a great signing for the club," said Townsend. "It is exciting what he could do for the guys off the field, in terms of learning from a world-class athlete with his preparation, exercise and things like that.

"He's a very positive and optimistic individual so he'll lift the group. And the generating of interest globally from rugby but also non-rugby supporters already has been terrific, and that's great for the club. It also says something about the club's ability to sign someone like Carlin because I know Toulon were interested in him a season ago."

Isles will undoubtedly attract a lot of attention to the Glasgow club, but Townsend dismissed a suggestion that the box office had been the prime consideration in securing the player's services.

"The signing was about his rugby," said the coach. "Yes, a lot of that is potential and we have to make sure that we improve him. If you speak to coaches who have worked with him and coached against him, they all say how different he is now to when he came on the scene, I believe that we will get something out of him."

While Glasgow are firmly in the mix for a RaboDirect PRO12 play-off place, they have lacked spark this season, particularly as far as try-scoring is concerned. Yet while it would do their play-off hopes a power of good if they could secure a win against Leinster in Dublin tonight, Townsend admitted that he is not expecting a free-flowing exhibition.

"We have to go with physicality," he stressed. "We have had some good games with them in the last few seasons and were getting closer and closer to beating them last season. We went close in the semi-final [last May] and then managed to beat them at the start of this season.

"The games have been really good to watch and very physical, especially around the breakdown, so we know we have to front up in that area. Leinster are one of the best attacking teams in Europe so if you give them quick ball you'll get damaged."

With a scrap on the cards, Townsend has picked a pack of street fighters. All three back-row players - James Eddie, Rob Harley and Josh Strauss - have played at blindside, as has lock Tim Swinson, who comes back into the side after his shift as an unused replacement for Scotland in Rome last weekend.

Tommy Seymour and Chris Cusiter have also been released for club duties by national coach Scott Johnson, with Townsend explaining that both have had relatively little match time lately, so it would be misleading to look for ulterior reasons for their selections.

"It's great for them that they get to play," said Townsend. "Two weeks ago we played Cardiff and they had Gethin Jenkins and Sam Warburton playing and that helped them because they played well for Wales against France a week later."

Of just as much significance is the return of Peter Murchie. The full-back, who was capped on Scotland's tour to South Africa last year, was in outstanding form at the start of the season and could have a big part to play in the run-in to the end of the season.

Townsend also revealed that Peter Horne, who has been out of action with a knee ligament problem since that summer tour, is also expected to make his return in a club match within the next two or three weeks.