Zambrano was doing interviews with members of the Venezuelan media when he backed up into the swing of White Sox third base coach Joey Cora, who was hitting infield grounders.
The fungo bat slammed into Zambrano's right elbow and he was taken to a local hospital, where X-rays were negative, according to a source close to the situation. The extent of the injury, and any effect it might have on Zambrano taking his turn in the rotation, is unknown.
"He wasn't able to throw," National League manager Phil Garner said. "Let's just leave it at that."
He was asked if he was kidding.
"I wish I were," Garner said.
Zambrano was not available for comment.
The accident caps a tough-luck first half for the Cubs, who lost first baseman Derrek Lee for more than two months with a broken wrist suffered in a freak collision at first base and have been without aces Kerry Wood and Mark Prior for most of the season. It appears Wood is now likely out for the season, and the controversy surrounding Dusty Baker's managerial status has been a distraction of late.
It became clear something was off when Reds pitcher Bronson Arroyo came in to pitch the fifth inning of the All-Star Game. Arroyo, who had pitched on Sunday and said he celebrated a little too hard upon his arrival in Pittsburgh, said he made it clear to Garner that he did not want to pitch on just one day of rest.
"I just went out too hard the other night," Arroyo said before the game. "I told him if he can get by without me, get by without me."
But with Zambrano, who would have been pitching on three days of rest rendered unavailable, Arroyo got the call.
"That kind of put a cramp in our plans," Garner said.
And possibly in the plans on the North Side.
Perhaps nobody this side of Minnesota's sensation, Francisco Liriano, has been as dominating in recent months. Since April, Zambrano is 7-1 with a sub-two ERA. Overall, the 255-pound right-hander is 8-3 with a 3.24 ERA, and his 124 strikeouts are third-best in the Majors.