PHOENIX (AP) - Arizona ace Brandon Webb is headed to the 15-day disabled list with tightness in his pitching shoulder.

The Diamondbacks decided to make the move, retroactive to Tuesday, after Webb tested the shoulder by playing catch on Sunday morning.

Webb said he's confident the injury will heal quickly.

The club planned to make a corresponding roster move after Sunday's game against the Los Angeles Dodgers.

Arizona manager Bob Melvin said the Diamondbacks wanted to be cautious with Webb, who won the 2006 NL Cy Young Award and finished runner-up the last two years. Webb has been Arizona's workhorse since 2004, pitching at least 208 innings in each of the past five seasons.

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