The Argentine star picked up the injury on Saturday in Barcelona's 2-2 draw with Valencia. Fatigue will obviously be a cause of major concern as the season progresses as Valverde would want a player like Messi to be at the top of his game as the business end of the season approaches.
Messi returned to training on Tuesday and was included in the squad for the first-leg match at Camp Nou Stadium, although it was still unclear whether he had fully recovered from a right leg injury.
Barcelona have confirmed their players will wear shirts featuring Chinese characters when they take on Real Madrid in the first leg of the Copa del Rey semi-final.
"It's harder when you have all the players available, because it means you have to leave someone out", Solari said.
It was an unusual delay by the club, which normally is quick to release reports about its players' injuries. Barcelona will obviously look to win every competition they are a part of to maintain their sky-high standards and over dependency on one man's genius can be harmful.
But the way Barca play allows them to save energy more than other clubs as they have great ball possession and force their opponents to run a lot.
There is little doubt Benzema will start, as he has six goals in the last four matches.
Lionel Messi has scored 12 goals in his last nine games.
Their 5-1 thrashing of Real Madrid earlier in the campaign led to Julen Lopetegui losing his job as coach just months after taking over.
Leo Messi was instrumental in Barcelona's Copa Del Rey matches, as usual, helping them overcome teams like Sevilla. The next two will come back-to-back, with the second leg of the Copa del Rey scheduled for February 27 before a La Liga fixture on 2 March, both at the Santiago Bernabeu.
"I don't think it changes anything", he added when asked how a hypothetical Messi absence could influence proceedings.
If Messi plays it will be because he is fit.
"I don't think there is a favorite in a semifinal between Barcelona and Real Madrid".