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Ross Detwiler threw the equivalent of three innings in a bullpen session on Wednesday. “He looked great,” Nationals Manager Davey Johnson said. Detwiler will throw another bullpen in two days before he heads to Viera on Monday to start in the instructional league. Based on the limited number of games left in the season and despite the left-hander’s hope to return this season, Detwiler may not pitch in a major league game again this season, Johnson said.

“He’d need to have four days off and then there’s only one game or two games left,” Johnson said. “I don’t see the point in coming out and having him for one game probably. But that’s going to be a decision made down the road.”

Detwiler has been out since July 4 with a herniated disk in his lower back. After the best season of his career in 2012, he has made only 13 starts and posted a 4.04 ERA in an injury-plagued 2013. Depending on Detwiler’s instructional league start, Johnson believes the left-hander might remain in Viera under the eye of the Nationals’ trainers and medical staff.

Johnson believes the injury first began during Detwiler’s stint with Team USA during the World Baseball Classic and worsened during the season. He wants Detwiler to log enough innings this season to prove that his back has improved.

“We need to see if this injury is going to resurface,” Johnson said. “As many starts as he can get, appearances, is I think important. He needs to be reliable next year.”

General Manager Mike Rizzo wouldn’t rule out Detwiler’s return this season. If Detwiler returns to the major leagues, Johnson has said he would pitch out of the bullpen.

“We’re going to see where he’s at after he pitches Monday,” Rizzo said. “… He has to pitch in a game situation and be stretched out to throw a certain number of pitches before we can pitch him in a big league game.”

The Nationals still want Detwiler to play winter ball after the season, an idea he has been opposed to, Johnson said. “We would like for him to get some additional innings,” Rizzo said.