Nationals pitcher Stephen Strasburg did not throw a bullpen session as hoped this week and instead was placed on the 15-day disabled list on Wednesday with a strained lat muscle.

Strasburg was examined by a doctor this week and there remains “tenderness and discomfort” in the muscle, according to Washington manager Davey Johnson. Strasburg is not eligible to return until June 16. He had been pitching with the injury for several starts, but was pulled from a May 31 game against the Atlanta Braves after just two innings.

Strasburg played catch on Wednesday, Johnson said, but the team didn’t want him on a mound. It is unclear if the Nats will recall a reliever from the minor leagues to fill Strasburg’s spot on the roster or just wait until they need to add another starting pitcher on Saturday for an afternoon game against the Minnesota Twins.

“It’s a strain. It’s quite tender and we want to get past that before he gets back on the mound,” Johnson said. “Hopefully that’ll be soon.”

Injured left-handed pitcher Ross Detwiler is not a candidate to make that start. He remains on the disabled list with a right oblique injury. He did throw a bullpen session on Wednesday and did well, Johnson said, but hasn’t pitched since a May 15 game in Los Angeles and needs a minor-league rehab start before returning. That start should happen on Monday and likely would be at Syracuse – though low-A Hagerstown is at home, too. Both Double-A Harrisburg and Single-A Potomac are on the road that day.

Johnson did offer a qualifier. The last time Detwiler threw a bullpen session he woke up the next day still stiff. So a start could come as soon as Sunday and would ideally be between 40 and 50 pitches. Johnson didn’t think Detwiler would need more than one rehab start to return to the big-league rotation.

Saturday’s starter will come from Syracuse, Johnson said. The obvious candidates are right-hander Ross Ohlendorf, a former major-leaguer who hasn’t pitched since last Thursday, and Danny Rosenbaum, 25, who has a 3.48 ERA for the Chiefs in 11 starts. He pitched on Monday, but isn’t on the 40-man roster. Washington does have an open spot if it wanted to go in that direction.’s Ken Rosenthal is reporting that Ohlendorf is the team’s choice. He has a 4.32 ERA in 11 starts at Triple-A. Ohlendorf has 108 appearances and 73 starts over parts of six major league seasons with three teams (Yankees, Pirates, Padres). Rosenbaum has never pitched in the majors and lasted just 1 2/3 innings in his most recent start at Syracuse.

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