Scotland quartet Alan Hutton, Gary Caldwell, Graham Dorrans and Steven Whittaker missed training on Sunday but could yet face Spain on Tuesday.[LNB] The four players are struggling for fitness ahead of the crucial Euro 2012 qualifier against the world champions at Hampden Park.[LNB]Tottenham full-back Hutton, Wigan defender Caldwell, West Brom midfielder Dorrans and Rangers utility man Whittaker were not risked in Sunday's session but assistant boss Peter Houston was confident that "the majority, if not all" would be available for selection.[LNB]Caldwell played 75 minutes of the 1-0 defeat to the Czech Republic in Prague on Friday, his first action of the season for club or country following a hip operation, and Houston did not rule out the former Celtic man making back-to-back appearances.[LNB]Houston said: "Caldwell has been feeling good, he knows he's been out for a while but nobody knows his body better than himself, and he was keen to do something today and he's putting himself up for selection."[LNB]Dorrans is nursing a hamstring problem while Barry Robson is suspended, but there was some good news as Manchester United midfielder Darren Fletcher, who took a knock in Prague, was fit to train on Sunday.[LNB]Houston hailed the performance of the team against the Czechs despite the result, and said: "We were disappointed after the defeat, that's only natural. However, the players worked their socks off and were unlucky to lose to a goal from a set play.[LNB]"We are keen to play the world champions in what will be a difficult game. Footballers like to play at the top level and nobody is better than the world champions."[LNB]National team boss Craig Levein was criticised for the negative approach adopted against the Czechs but Houston said: "The only regret we've got is that we've lost the game. It's over and done with now, we can't look back, we've got to look forward and what a way to look forward - playing Spain at Hampden.[LNB]"We've got to put that to bed and start to think positively and take something from that match.[LNB]"Playing Spain will require a different outlook, a different type of game where we have to try to attack, we tried to attack but in a different way in the Czech Republic and played some good stuff and did OK."[LNB]Asked who had formulated the tactical plan, Houston added: "It is always the manager at any football club, he comes up with what he thinks is the best way to get something from the game and I thought we were unfortunate. We lost to a set play which normally we're quite strong on.[LNB]"It's over and done with, we've lost the match but what we'll do now is bring on Spain, and we'll do our very best to try to get something."