Lionel Messi could miss Barcelona's Copa del Rey semi-final second leg against Valencia as he will reportedly undergo a kidney operation on Tuesday.
According to Sport, Barca have given Messi two days off so he can be cured of the renal colic which ruled him out of the Club World Cup semi-final against Guangzhou Evergrande in December.
Although it is only a minor operation, which should see him discharged the same day, it would rule Messi out of the trip to Mestalla a day later, with the Catalans 7-0 up from the first leg of the tie.
