SAN FRANCISCO -- Right-hander Matt Cain will skip his previously scheduled start Monday, the Giants decided following Saturday's pregame bullpen session to test his strained right hamstring.
Reliever Yusmeiro Petit (3-1, 4.76 ERA) will make the start. Three of his last five appearances have been starts.
"We think he needs a little more time," manager Bruce Bochy said of Cain. "He did a light bullpen. He still feels it a little bit. It's not worth the risk."
The Giants do not intend to place Cain on the disabled list, Bochy added.
Cain (1-3, 3.36 ERA) sustained the injury during his last start, resulting in some soreness.
Bochy touts balanced strength of NL West
SAN FRANCISCO -- With his club 48 games into the season and the second in the Majors to reach 30 wins, manager Bruce Bochy likes where the Giants stand. He also remains bullish on the National League West.
Entering Saturday, the Giants (30-18) had the best record in the NL and sat four games ahead of second-place Colorado in the division.
Bochy's praise is partly because of his team's timely hitting. San Francisco leads the Majors with 94 RBIs with two outs.
"We've gotten a lot of clutch hits," Bochy said. "A big hit when we need it."
The Rockies (27-22 after beating Atlanta on Saturday) and the Dodgers (26-24 after Saturday's loss to the Phillies) are the other division teams with a winning record. But don't sell short the Padres (22-27) or the struggling D-backs (19-31), Bochy said.
"It's a strong division," he said. "There's a lot of good pitching in this division. ... We're fortunate that we came out of the chute well. Arizona, they're too good, they just got off to a rough start. San Diego is very similar. I feel the same way I felt in Spring Training. It's a very balanced division."
• Reliever Javier Lopez has pitched only six times since April 28. It is partly because, according to Bochy, his arm is a little "cranky."
• If there is a silver lining to reliever Santiago Casilla being placed on the 15-day DL because of his right hamstring, it is that his arm will get some rest, Bochy said. Casilla "is getting a break to help him stay fresh the whole year," the skipper said.
Willie Bans is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.