The Oakland Athletics have placed pitcher Rich Harden on the 15-day disabled list because of a strained left oblique muscle. The move is retroactive to May 14, one day after Harden was hurt in the fourth inning of a start against the New York Yankees. He allowed five runs on four hits with one walk and four strikeouts over 3 1/3 innings of the 9-4 setback. Harden owns a record of 2-3 with a team-best 2.80 earned run average in seven starts this season. The 23-year-old righthander ranks fourth in the American League with 42 strikeouts. The Athletics filled the roster spot by recalling pitcher Seth Etherton from Triple-A Sacramento. Etherton was 1-2 with a 2.76 ERA in six games, including five starts, with Sacramento. He could start for Oakland in Harden's next scheduled spot in the rotation on Wednesday against Boston. The 28-year-old righthander was signed by the Athletics as a free agent on November 1, 2004 and was 0-1 with a 5.40 ERA in six games this spring. He made his big league debut with Anaheim in 2000 and has also pitched in the majors with Cincinnati in 2003.