HOUSTON -- Cubs pitcher Carlos Zambrano went so far Wednesday as to invite reporters to watch him throw his next side session.

Zambrano and the Cubs displayed varying degrees of anger -- from red-hot to blue-flame hot -- over a published report that said the ace of the pitching staff had stiffness in his right shoulder and neck area.

The report listed "shoulder" first, and that's what set the Cubs off.

Zambrano and the Cubs' brass said Zambrano has had nothing more than a stiff neck since his start Saturday against the Pirates. They attributed it to the way he slept.

"I'm not hurt," said Zambrano, who later flexed his muscle. "I feel great. Just check out my outing Friday."

Zambrano will pitch as scheduled in Friday's series opener at Pittsburgh.

"Zambrano?" asked manager Lou Piniella. "He's pitching Friday. I don't know where all this stuff came from, but I'll tell you this: Larry Rothschild (the pitching coach) told me yesterday that he had the best throw day that he's had all year.

"Physically, there's nothing wrong. He's ready to go Friday in Pittsburgh. He had a really, really nice throw day yesterday in the bullpen. There's never been any concern. There's never even been a question of concern. Nothing. I'm more concerned about my shoulder than I am his."

Zambrano lasted 4 innings in Saturday's 7-6 loss at Wrigley Field.