Barcelona coach Gerardo Martino has voiced his concern for star player Lionel Messi after the Argentine was seen vomiting during his country's goalless draw with Romania on Wednesday.
Messi was also sick on the pitch recently in Barca's 3-1 defeat at Real Sociedad and Martino admitted the player has visited specialists to try and resolve the problem.
"It is not a normal situation, but there is no alarm. He has been to see specialists but as yet they haven't found a solution.
"The important thing is that it doesn't affect him from doing his job. It is something that he has had for a while now."
Messi was just one of a number of Barca players away on international duty in midweek with Brazilian duo Neymar and Dani Alves only returning to training on Friday having represented their country against South Africa in Johannesburg.
And Martino lamented having such little time to prepare for the Catalans visit to relegation threatened Valladolid on Saturday.
Barca currently trail leaders Real Madrid by a point, but can take top spot for 24 hours with a win as Madrid are not in action until Levante visit the Santiago Bernabeu on Sunday.
"It has been a short week. The majority of the players arrived back on Thursday and some not even till Friday.
"We have only been able to speak about the game for one day, but that should not be an excuse. We need to concentrate, play well and win.
"The game worries me because of what it means for our opponents. They are fighting in the bottom part of the table, but they have only lost two games at home. They are very strong at home."
Martino hinted that Neymar is likely to rested from the start having completed the 90 minutes against South Africa and with Tuesday's Champions League last 16, second leg against Manchester City in mind.
Gerard Pique is included in the squad for the first time in three games, though, as he has overcome a calf problem.