Aaron Ramsey will miss Wales' crunch tie in Slovakia due to injury.
The former Arsenal midfielder did train on Wednesday morning after reporting a groin problem, but Giggs' squad flew to Slovakia without him.
Manager Ryan Giggs said he hoped Ramsey will recover in time for the Euro 2020 qualifier with Croatia on Sunday.
''He did a bit of training and the physio has stayed back to work with him,'' Giggs said.
''We are hopeful that he will be available for Sunday. He has a chance.''
Ramsey's unavailability has been a constant theme of Wales' European Championship qualifying programme, with the 28-year-old yet to play a single minute of the Dragon's campaign.
Wales trail group leaders Croatia by four points and are three adrift of Slovakia and Hungary.
''We need to play better, but the circumstances were different in the summer,'' he said.
''Some players hadn't played for five weeks. You can always lose in football, but it is how you come back that's important.''
UEFA had originally ordered the Slovakia game to be played behind closed doors, with Slovakia fans found guilty of making ''illicit chants'' during last month's victory in Hungary.
Slovakia won their appeal against the fans' ban, saying the chants had been political rather than racist, and there will be a 20,000 sell-out crowd at Trnava's Anton Malatinsky Stadium.
Gareth Bale is back on international duty amid reports in Spain that he is unsettled there and wants to leave Real Madrid.
Asked if he is playing with anger at the moment, Bale said: ''You play with a lot of emotion.
''Anger comes into it of course, but I haven't got anything to clear my mind about.
''I try and give my best whether here or in Madrid and I will continue to do that.''