Everton defender Matthew Pennington was injured in their friendly with Real Betis.
Pennington will be assessed on Everton's return to England after suffering a hamstring injury against Real Betis on Saturday.
The defender, 21, limped off in the 78th minute of the Dresden Cup encounter as the Blues went on to lose 4-3 on penalties after a 1-1 draw.
Pennington, who was replaced by John Stones, will now fly back with the squad and be assessed at Finch Farm to establish the full extent of the problem.