Martin O'Neill has admitted Aston Villa's UEFA Cup victory at Slavia Prague has left him with some tough calls to make as he prepares for the visit of Middlesbrough on Sunday.

O'Neill rested his big hitters Brad Friedel, Luke Young, Martin Laursen, Gareth Barry and Nigel Reo-Coker, while he was also without the injured James Milner, who is fit to return on Sunday.

It did not harm Villa at all as they ran out 1-0 winners in the Czech capital and now O'Neill has a tough decision to make on who returns to the team.

Brad Guzan, Zat Knight, Curtis Davies, Craig Gardner, Moustapha Salifou and Steve Sidwell all impressed after being called up and now O'Neill has to decide just how to change a winning side.

He said: "The performances in Prague have certainly given me food for thought. No question about that.

"If we are ever going to be good enough to challenge the leading clubs then we have to have the squad and have the ability to rotate and know you are not making the side weaker.

"I said I would make changes against Prague but it is always a bit of a risk.  I wanted to freshen things up in the team and I wanted the players coming in to be involved in a very important game.

"It was a gamble but I thought the players played exceptionally well. There is an art in it only if you win games.

"I could not be more pleased. This is what I wanted, a little bit of competition for places. In two seasons here at Villa this is something that we've not been able to achieve.

"At the moment we do not have it to the level of the sides we are trying to compete against. But overall it is very encouraging.

"It could have backfired but I thought in mid-field Salifou, Sidwell and Gardner could give us a freshness but would tire in the second half which is exactly what happened in the game. Their overall contribution was excellent."

Guzan, standing in for compatriot Friedel in goal, kept a clean sheet and came in for plenty of praise from O'Neill.

"Brad Guzan was absolutely brilliant. I've had no qualms about him. I think he is a quality goalkeeper in the making," the Northern Irishman added.

"The performance against Slavia Prague might have shown a reason why I spent a long time chasing him. He is brave and desperate to succeed.

"He is the latest of a long line of American goalkeepers who have been brilliant in the Premier League. He is eager to go and his performance in Prague will have given him as big a lift as he could possibly get.

"As a goalkeeper there is no hiding place and against Slavia Prague he was majestic. I never thought he would be a risk. What he did in Prague did not surprise me."