Barcelona have confirmed that Lionel Messi is undergoing further tests on kidney problems which first emerged in December but expect the forward to return to training on Wednesday.
The Argentina international missed part of the Club World Cup in Japan as a result of renal colic, an abdominal discomfort commonly caused by kidney stones.
Reports emerged in Spain on Monday suggesting Messi could face minor surgery in order to correct the problem, which has reportedly persisted in recent weeks despite the 28-year-old missing only one match since the turn of the year.
"Leo Messi will be submitted for different tests on Monday and Tuesday to assess the development of the kidney problems suffered in December," a Barcelona statement read.
"On Wednesday the player will return to training with the first team."
Messi could be rested for the Copa del Rey semi-final second leg against Valencia on Wednesday as Barca hold a 7-0 aggregate lead.