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05/11/08 3:28 PM EST

Davis sharp in rehab start

Lefty had surgery to remove cancerous thyroid last month

CHICAGO -- Doug Davis took a big step towards rejoining the D-backs when he tossed 4 2/3 innings for Triple-A Tucson on Saturday night.

The left-hander, who had surgery to remove a cancerous thyroid on April 10, allowed two runs on six hits with a walk and a three strikeouts.

"He felt good," D-backs manager Bob Melvin said. "His endurance was there, his arm slot was good. We're monitoring his endurance every time out, and yesterday it was good."

Davis is slated to make one more rehab start before being activated. The D-backs will push that start back until Friday or Saturday. That presumably is so that they can line him up to take rookie Max Scherzer's spot in the rotation. With the scratching of Randy Johnson on Sunday and Monday's scheduled off-day, each D-backs starter is getting two extra days of rest this time around.

The D-backs would like Davis to get his pitch count up to around 100 pitches in his next outing so that they do not have to worry about how deep he can go in his first start back.

Davis made two starts before undergoing surgery, and was 1-1 with a 3.72 ERA.

"I think it's almost a given that it would lift everybody's spirits seeing him back here pitching in a big league game," Melvin said.

While it seems all but certain that Davis would take Scherzer's spot, Melvin did not wish to say that yet. Scherzer allowed just one unearned run over six innings in his start Saturday against the Cubs.

"We still think he's going to have a tremendous career here," Melvin said. "Whether or not he's in the starting rotation when Doug comes back is still kind of yet to be determined."

Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.