"He has a stomach bug," Giants head coach Tom Coughlin told reporters. "Hopefully it is just a 24-hour deal and he will feel better tomorrow."

Manning passed for 330 yards and three touchdown passes in the Giants' 37-20 win over the top-seeded Green Bay Packers in the divisional round of the playoffs to get his team one win away from a berth in the February 5 Super Bowl in Indianapolis.

New York's leading wide receivers Hakeem Nicks and Victor Cruz were not worried about Manning's condition ahead of the showdown in San Francisco.

"I didn't really notice anything about him, honestly," Nicks, who caught a pair of long touchdown passes in last week's win over Green Bay, said at the Giants' practice facility.

"Apparently he had to leave because of his stomach but I don't feel like it was nothing serious. I don't think it's going to affect him at all. He's alright, he's as tough as they come."

Cruz said he did not think the interruption would affect the timing between Manning and his receivers.

"No, not at all," said Cruz. "As long as he'll be out here tomorrow and Friday and be out here working with us.

"It's tough to pull him away from this field. No matter how sick he was, he didn't want to leave the field today, but it's just one of those things where he had to."

(Reporting By Larry Finel; Editing by Frank Pingue)