MADRID, Feb. 3 (Xinhua) -- FC Barcelona coach Ernesto Valverde has warned that Leo Messi is a slight doubt for the first leg of Wednesday's Copa del Rey semi-final against Real Madrid on Wednesday night.

Messi underlined his importance to Barca once again on Saturday as he scored both goals to allow his side to come back from 2-0 down to claim a 2-2 draw against Valencia. However, he ended the game limping after receiving a blow to his right thigh to set alarm bells ringing at the Camp Nou.

"He has a problem, but we don't know its extent," Valverde said to the press after the game.

Pressed into giving more details, Valverde said the striker was "good, but we are going to carry out some tests to see how important the problem is. We hope he can get better."

"I don't know exactly what he's got and we will wait to see what the doctors say, although we don't think it is going to be very bad," commented the coach.

Valverde also commented that if Messi's injury had been serious he would have asked to be substituted "but he didn't say anything."

"If he's fit, he'll play, if he isn't someone else will play," he concluded.

Messi missed the first 'Clasico' of the season at the Camp Nou at the end of November, but Barca didn't notice his absence as Luis Suarez scored a hat-trick in a 5-1 thrashing of their traditional rivals.

Ousmane Dembele is another doubt for Wednesday's game as the French international missed Sunday's training with a fever and a reported throat infection.