However the Liverpool player is expected to be fit for their tournament opener against Slovakia on 11 June.
Blackburn defender Adam Henley has left Wales' Euro 2016 finals training camp in Portugal with an undisclosed injury.
Walsall striker Tom Bradshaw is ruled out of the tournament in France because of a calf injury, while there is still a doubt over midfielder Joe Ledley.
Ledley hopes to recover from a leg fracture and be named in Wales' Euro squad when it is announced on Tuesday.
The Crystal Palace player injured his leg on May 7 and boss Chris Coleman admits he is "50-50" to make the finals, which start for Wales against Slovakia in Bordeaux.
Danny Ward missed part of Wales' training camp in Portugal as the Liverpool goalkeeper recovered from a knee injury that forced him to miss the end of the season.
Preston goalkeeper Chris Maxwell travelled to the training camp in the Algarve as a precaution but Ward has since rejoined the squad.
Henley, 23, was always an outsider to make the final 23-man squad while Bradshaw - Walsall's 20-goal top scorer - has also left the camp in Portugal, where Coleman's initial 29-man preliminary squad is down to 27.
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Midfielder Joe Allen is a doubt for Wales' Euro 2016 warm-up match in Sweden because of a minor knee injury.