"The Giants are on the hook for two more years and nearly $50 million with Barry Zito. But his spot in the rotation is clearly on a start-by-start basis.

Although Zito continues to prepare for his next assignment Sunday in Cincinnati, the Giants are listing the game as "to be determined." And they are being cagey about it.

"We're just leaving it open," Giants manager Bruce Bochy said. "That's all."

Bochy said Zito is healthy and the left-hander seemed surprised at the confusion, saying he planned to throw his usual session off a bullpen mound on Friday.

Zito has gotten knocked around for 14 runs over his last two starts, derailing momentum from the three consecutive victories he posted after coming off the disabled list June 28. He is winless with a 6.75 ERA in four career starts at lively Great American Ball Park.

If the Giants opt to replace Zito with left-hander Jonathan Sanchez, they would be pitching him one day short of regular rest. Sanchez threw 95 pitches in six innings of a rehab start Wednesday for Triple-A Fresno, and was not a finished product.

"He was in and out of his delivery," said pitching coach Dave Righetti, after looking at reports but before reviewing film."