(Reed Saxon / AP)

Left-hander Ross Detwiler could miss his next start with back stiffness, an injury that led the Nationals to recall reliever Erik Davis this morning and send utility man Jeff Kobernus back to Class AAA Syracuse.

Manager Davey Johnson wanted an extra pitcher as he keeps swingman Ross Ohlendorf, who pitched two innings last night, in reserve. If Detwiler cannot make his start scheduled for Wednesday, Ohlendorf would “probably” take his place, Johnson said.

Detwiler will receive treatment on his back, and the Nationals are aiming for him to throw his usual side session either Sunday or Monday. If Detwiler’s back stiffness prevents him from throwing the bullpen session, he would not be able to start Wednesday.

Detwiler felt the soreness on the left side of his lower back, opposite from the oblique strain that forced him to the disabled list for a month. He had not experienced the soreness prior to last night. Detwiler has made four starts since returning June 13, going 2-2 with a 7.32 ERA. Friday night, Detwiler allowed three runs, two earned, over five innings, throwing 98 pitches.

“I thought he threw the ball well,” Johnson said. “I didn’t see anything bothering him during the game.”

With Detwiler’s status in question, the Nationals added Davis for his second stint in the majors. Davis, 26, made five appearances after the Nationals called him up in early June, striking out seven as he allowed three runs in 4 1/3 innings. Davis has a 3.77 ERA in 28 2/3 innings at Syracuse this year.

“I guess you’re always surprised,” Davis said. “You never really expect it. It’s a good surprise.”

Kobernus, whom the Nationals called up in late May, will return to Syracuse after he went 4 for 23 with four walks over 15 games. The Nationals now have only a four-man bench, at least until Bryce Harper returns Monday and perhaps beyond. Johnson is not worried about that.

“There’s nobody in the lineup I pinch hit for, really,” Johnson said.

The Nationals also made official their move of calling up Taylor Jordan from Class AA Harrisburg and sending first baseman Chris Marrero down to Syracuse. The Nationals will have to make another swap Monday, when Harper returns.

In other news at Syracuse, outfielder Eury Perez has been placed on the disabled list.