Washington Nationals manager Davey Johnson said righthander Chien-Ming Wang could be sidelined longer than expected.
Johnson said he does not expect Wang to be back on the mound for a month because of the severity of his hamstring injury suffered last week.
"He's got a lot of bleeding in there," Johnson said Wednesday.
Wang was hurt while attempting to cover first base during Thursday's spring training game against the New York Yankees.
The 31-year-old Wang had a solid comeback season in 2011 after missing the entire 2010 campaign with shoulder problems, going 4-3 with a 4.04 ERA in 11 starts. Wang spent his first five seasons with the Yankees, emerging as one of the club's top hurlers. He posted back-to-back 19-win campaigns in 2006-07 but has just 13 victories since.