Thome was hurt during Wednesday night's win in Detroit and was not in the lineup for Thursday afternoon's series finale.
"It's about the same as it was last night," said Thome, who had ice and electrical stimulation on his leg before Thursday's game. "Hopefully, it will only be a few days."
White Sox manager Ozzie Guillen said the team will wait several days before considering putting Thome on the disabled list. Thome is hitting .294 with 36 homers and 91 RBI.
"We can play without him for three or four days -- we've done it before -- and then we can bring up some kids on Sept. 1," he said. "I don't think we are worrying about the DL with him right now. This happened in spring training, and he came back fast."