Cubs starter Carlos Zambrano left Sunday's game against the Florida Marlins with a left hamstring strain.
Zambrano led off the fifth inning with a bunt single, but appeared to hurt himself while stretching to beat the throw from Marlins pitcher Ricky Nolasco.
Pitcher Rich Harden pinch-ran for Zambrano, then scored four batters later on Derrek Lee's grand slam to give Chicago a 6-2 lead.
Zambrano allowed two runs on four hits in five innings, striking out three and walking one. Angel Guzman relieved Zambrano in the sixth.