Real Madrid forward Cristiano Ronaldo limped off towards the end of a training session on Tuesday, prompting speculation about his fitness for Saturday's Champions League final.
The former Ballon d'Or winner has been plagued by a thigh injury that forced him to miss three games in April.
He came off at half-time during Real's final La Liga game of the season.
Real Madrid face Atletico Madrid in Milan this weekend in a repeat of the 2014 final, which Real won.
Portuguese international Ronaldo, 31, has scored 51 goals for Real this season.