PHOENIX — Arizona Diamondbacks ace Brandon Webb will skip his next start because of shoulder stiffness.

"For a guy like him, this isn't something you can mess around with," manager Bob Melvin said before the Diamondbacks played Colorado yesterday. "I'd hate for him this early in the season to go out there and pitch with some soreness already, or some stiffness."

Yusmeiro Petit will take Webb's scheduled start Saturday night at home against the Los Angeles Dodgers.

Webb, whose 22 victories led by National League last season, experienced stiffness in his shoulder in the fourth inning of Arizona's 9-8 opening day victory Monday over the Rockies.

The 2006 NL Cy Young winner blamed problems with his arm angle, resulting in a diminished sinking fastball, for his poor outing. The right-hander allowed six runs on six hits, including two homers, in four innings.

"He played catch yesterday and was OK," Melvin said, "then came in today and it was bothering him a little bit, so I'm going to try to be proactive on this one."

No medical tests are planned as yet.

PADRES

Tom Garfinkel, a former executive with NASCAR's Chip Ganassi Racing Teams and the Arizona Diamondbacks, was introduced yesterday as the San Diego Padres' president and chief operating officer. The 40-year-old Garfinkel will oversee all nonbaseball operations for the club.