STEVE CLARKE has revealed Everton youngster Nathan Patterson is a doubt for Scotland's World Cup play-off match against Ukraine next week.

The national team take on Ukraine on June 1 in the World Cup play-off semi-final match with the winners taking on Wales for a spot in the finals.

But, Scotland will likely be without former Rangers starlet Patterson for the match as he faces a race for fitness.

Kieran Tierney hasn't made the squad after knee surgery, while Kenny McLean misses out through a broken toe.

Clarke explained the injury impact on his selection after the squad announcement this afternoon.

He said: "It's a big blow for everybody just finding out today but we've known for a little while Kieran wouldn't be involved.

"It's disappointing for Kieran and for us.

"At some stage over the four or hopefully five matches, Nathan will be fit to play. His return to play is imminent and it will just come down to match fitness.

"I would put him down as doubtful for the Ukraine game.

"Billy will be fine. Obviously disappointing for someone like Kenny McLean who has missed out again after picking up a broken toe.

"That's disappointing because he's a crucial part of the squad."

With Patterson a doubt, it leaves Stephen O'Donnell and Anthony Ralston as possible starters at right-back for the crucial Hampden clash.

Goalkeepers: Clark, Gordon, Kelly, Marshall

Defenders: Cooper, Hanley, Hendry, Hickey, McKenna, O'Donnell, Patterson, Ralston, Robertson, Souttar, Taylor

Midfielders: Armstrong, Ferguson, Gilmour, Jack, McGinn, McGregor, McTominay, Turnbull

Forwards: Adams, Brown, Christie, Dykes, Stewart