Correction: An earlier version of this article misidentified a player for the Nationals. He is Chad Tracy, not Paul Tracy. This version has been corrected.

Stephen Strasburg allowed a first-inning run in another bumpy start. (Kevin Liles/Getty Images)

Six times this season, Washington Nationals starter Stephen Strasburg has taken the mound to begin a game and only once has he met the sky-high expectations set for him. His first-inning struggles have continued, his command has wavered at times and his aggression has been lacking.

After Monday night’s 3-2 loss to the Atlanta Braves, Manager Davey Johnson said Strasburg was dealing with tightness in his right forearm, a possible reason for his uncharacteristic four-walk performance and wavering command. Johnson said Strasburg was examined by medical staff following the game and would receive medication.

“He was still throwing good but his command was way off so I knew something was off,” said Johnson, adding it was too early to tell if Strasburg would miss his next start scheduled for Saturday. The Nationals have been cautious in the past with Strasburg, who had elbow ligament replacement surgery in 2010.

Strasburg, who shook his arm more than normal between pitches, insisted he felt fine on the mound. His said his command issues were because of a breakdown in his mechanics.

“I’m not missing my next start,” he said. “I’ll tell you right now.”

The game was ultimately lost in the seventh inning when Tyler Clippard, nursing a tie game, walked leadoff hitter Gerald Laird, who scored three batters later on a sacrifice fly by Andrelton Simmons. All three runs scored by the Braves started as leadoff walks. But Strasburg’s apparent forearm discomfort was more important than the Nationals’ fourth straight loss to their stiffest division rival.

“That overrides everything,” Johnson said. “Hopefully he’s going to be all right. We’ll just have to wait and see.”

Strasburg has struggled in the first inning, when he has a 10.50 ERA this season. But from the first batter of Monday’s game, his command was visibly off. He fell behind on the first pitch to four of the five batters. On six pitches, he walked leadoff hitter Jordan Schafer, who stole second base two batters later with Justin Upton batting. Upton’s single to right plated the game’s first run.

Strasburg escaped further damage in the inning with a snap throw from Ian Desmond. Freddie Freeman followed Upton’s single with one of his own to left field, but on the relay, Desmond saw Freeman drift too far off first and fired a low throw to Adam LaRoche. He swiped at Freeman’s leg and first base umpire Tim Timmons pumped his fist to call Freeman out, even though on replays Freeman appeared to get back safely. The results could have been worse for the Nationals.

“I was pulling the ball,” Strasburg said. “Can’t really say why I’m having a tough time right now in the first inning, but I am. Just got to keep grinding and I’ll figure it out.”

Strasburg allowed another run in the fourth inning, which began with a Freeman walk and ended when Denard Span threw out Dan Uggla advancing to third base on a single by Laird. Freeman, however, scored on the play.

Facing his biggest jam of the night in the fifth inning, having allowed a leadoff double to Braves starting pitcher Julio Teheran and a walk to Schafer, Strasburg buckled down. After a mound visit from pitching coach Steve McCatty, he massaged a flyout out of Simmons on a slick running catch by Bryce Harper. Against Upton, baseball’s most powerful hitter this April, Strasburg attacked. With a 3-2 count, he blew a 96-mph fastball past Upton’s swinging bat. Then he coaxed a lineout from Freeman to Chad Tracy at third base in five pitches.

“Him being wild, I talked to [McCatty] and said ‘Will you talk to him? Because he doesn’t look right to me,’” Johnson said. “He was still throwing the ball real hard, but I told him when he went out for the sixth, get him out of this and I’ll get him out of there and get you a win.”

Strasburg finally hit a groove in the sixth. He struck out all three batters of the inning on 13 pitches, the only time in the game he retired the Braves in order. He blew two 97-mph fastballs past B.J. Upton and jogged off the mound.

But Johnson didn’t want Strasburg to throw any more. He was worried about his pitcher’s arm even though Strasburg didn’t complain of it. He fired 53 strikes and 40 balls. He allowed the leadoff hitter to reach base in each of the first five innings. Yet he allowed only two runs over six innings.

The Nationals could have given Strasburg more run support but failed against the rookie Teheran. LaRoche, the team’s slumping first baseman, led off the second with a single, his first hit in 27 at-bats. It was the first of four straight singles, which netted two runs.

But the Nationals couldn’t score any more. Two base-running mistakes hurt them. In all, they stranded six runners, grounded into a double play and went 2 for 9 with runners in scoring position. In Strasburg’s starts this season, the Nationals have scored only 1.83 runs per game, by far the worst run support of his career.

After Strasburg left the game, Clippard coughed up the winning difference.

“It’s one of those things, I’ve got all the confidence in the world that runner is not moving off of first,” Clippard said of trying to recover from the leadoff walk to Laird. “I was just really up in the zone tonight and wasn’t able to execute to stop them from scoring.”

The Nationals were dealt another blow in the eighth when Jayson Werth exited the game, after fouling a ball off his left ankle, because of lingering cramping in his hamstring.

It is too early in the season for hand-wringing over another loss to the Braves. But the Nationals wanted to enact a small measure of revenge of their toughest division rival. Instead, discomfort in the arm of their prized starter darkened the cloud over the loss.