Alex Brandon/AP Alex Brandon/AP

If the Nationals right their season in the first week of June, they will have to do it without Bryce Harper.

The Nationals placed Harper, their 20-year-old force of nature, on the disabled today, the team announced hours before their Saturday night clash with the Braves. Harper has missed the past five games with bursitis in his left knee, which has caused pain and swelling that flared again Thursday as Harper attempted to take batting practice and jog in the outfield.

The Nationals are able to place Harper on  the DL retroactive to May 26, so will be eligible to return June 11.

Harper’s knee injury started May 13 in Los Angeles, when he collided with the right field fence in Los Angeles. Harper has played in nine games since, starting eight, but has clearly been a diminished version of himself. He has hit .226/.333/.452, which qualifies as monstrous compared to the Nationals’ average production but pales to his .287/.386/.587 line on the year.

Harper bounced in and out of the lineup until Sunday, playing though the pain, trying to come back three separate times. When he fouled a pitch off his left knee Sunday against the Phillies at Nationals Par, the swelling became unbearable.

The Nationals have called the injury a “day-to-day” ordeal, but it seems to be more serious, or will at least require more rest than originally thought.

According to the Nationals team doctors, there is no structural damage in Harper’s knee, and the bursitis will be solved with rest.  Manager Davey Johnson said yesterday Harper’s knee had not swollen to the point it needed to be drained.

The Nationals are 3-9 this year when Harper is not in the starting lineup, including their 3-2 victory last night. If there is any silver lining, the Nationals’ schedule becomes easier next week when they return home, with series against the Mets and Twins. The Nationals are also expected to receive a boost in the return of Jayson Werth, who last played May 2 because of a strained hamstring.

The replacement for Harper is right-handed reliever Erik Davis, who late last night tweeted his arrival to the majors. The Nationals need a pitcher in the short term because Craig Stammen pitched four innings in relief of Stephen Strasburg and Tyler Clippard threw 32 pitches in a single inning  last night. Davis could also be a replacement for Stammen if Stammen is required to take Strasburg’s spot in the rotation.

The Nationals acquired Davis, 26, when they traded utility infielder Alberto Gonzalez to the Padres at the end of 2011 spring training. They converted him a reliever last year, and his performance convinced them to add him to their 40-man roster this winter.

The Nationals have yet to hear further word on Strasburg, who flew back to Washington late Friday night for further on his strained right oblique. He exited the Nationals’ 3-2 victory after only two innings. He said he hopes to make his next start, but oblique injuries have a tendency to linger and knock pitchers out for weeks at a time.