Vern Cotter, the Scotland coach, has backed the Glasgow Warriors centre Mark Bennett to make a big impact on the Test stage when the 21-year-old makes his international debut against Argentina at BT Murrayfield tomorrow.

The selection of the Gray brothers, Richie and Jonny, to play together for the first time made immediate headlines but Bennett is one of 10 Glasgow ­players in the Scotland XV - another four are on the bench - and the only uncapped player in the side.

After some blistering recent displays, including a two-try contribution in Warriors' 37-10 demolition of Bath last month, it would have been a major surprise had the former Cumnock and Ayr player been left out against the Pumas.

"Mark gives us the qualities he has as a line-breaker," said Cotter. "He also gives us a couple of options on attack with his ability to beat defenders. He's playing with guys he plays with at club level as well.

"That first-five/centre combination is important and we have spoken quite a bit about his patience and build-up and he now gets his first opportunity in front of his home crowd. I know he will be relishing that moment and giving it his best."

Although still young, Bennett has been on the cusp of international selection for a long time. A prodigious talent, he was selected for the Scotland under-20 side when still just 17 and he was in the Scotland squad for last year's autumn programme but could not break into the side.

He would almost certainly have played on last summer's tour had he not been required for Scotland'sCommonwealth Games sevens squad in the summer.

"I was there or thereabouts but I didn't quite make it," said Bennett when asked about how close he felt to getting a cap in the past. "But personally, I feel I am in a much better position to perform now, not just go out and play. I am really looking forward to it."

The Warriors provide six of Scotland's seven backs for Saturday's game, the only exception being captain Greig Laidlaw, who plays for Gloucester. Bennett admitted that being in familiar company would make him more comfortable, especially playing alongside fellow centre Alex Dunbar, who comes back into the side after missing the summer games with a hip injury.

"It's easy for me coming into this, playing with Alex because I know what I'm going to get," said Bennett. "He's a big strong lad, he runs hard and he can really challenge a defence. I know how Alex is likely to play and I can react to that and play off him.

"He's a really easy guy to play with. He's really loud and communicative, which again makes it just that little bit easier for me to settle in."

The choice of Adam Ashe at No.8 is probably more surprising, but Cotter explained that Johnnie Beattie, the other specialist in the position, had been released to play for Castres against Toulon in order to regain match sharpness after a recent injury lay-off. Beattie will rejoin the national squad next week as they begin their preparations to play the All Blacks on November 15, but Cotter stressed that he was more than satisfied with what Ashe brings to the side.

"Adam gives us the ability to connect the play of forwards and backs," said the coach. "He is a player who stands out and gives us a wider option. We have players who play around rucks and carry ball there; the two Grays do that particularly well. But Adam gives us a pass-catch and he has good feet.

"He can play midfield and wider and link forwards and backs. Looking at his defensive performances I think he has really improved. He has gained weight and he is a competitor. He likes hitting hard and he will be looking forward to this game to show his qualities."

Daniel Hourcade, the Argentina head coach, has also named his team for Saturday's game. Although depleted by a spate of recent injuries, the Pumas include 10 of the side which started their in first Rugby Championship victory last month, when they beat Australia 21-17 in Mendoza.