When Nationals pitcher Stephen Strasburg left after two innings Friday night with a strained oblique, it wasn’t necessarily a good thing for the Braves. They’ve fared far better against him than most teams.

Sure enough, Strasburg was replaced by reliever Craig Stammen, who pitched four perfect innings in a 3-2 win against the Braves to open a three-game series at Turner Field.

Two hits apiece from Freddie Freeman and Ramiro Pena were the only hits for the Braves, who lost for only the second time in their past 10 home games, but for the third consecutive time against Washington. The Nationals pulled within 4 1/2 games of the first-place Braves in the National League East.

“Stammen hadn’t pitched in a while, and he went out there and gave them four strong innings, mowed right through us,” said Freeman, who hit a leadoff homer against Strasburg in the second inning, and flied out just before the right-field wall off closer Rafael Soriano to start the ninth.

B.J. Upton then struck out and Brian McCann grounded out to end the game.

The badly slumping Upton pinch-ran for Evan Gattis in the seventh inning, when Gattis represented the potential winning run before the Braves whiffed away a prime scoring opportunity.

After Freeman hit an RBI single and Gattis and McCann were hit by Tyler Clippard pitches to load the bases in the seventh, Clippard struck out Dan Uggla and Chris Johnson consecutively to quash the rally and deflate a crowd of 36,650.

“We had a chance, we just couldn’t put the ball in play,” Braves manager Fredi Gonzalez. “Bases loaded with one out, got him on the ropes a little bit, just didn’t put the ball in play.”

The Braves have three of the NL’s top four individual strikeout totals, including league leader Uggla (68). B.J. Upton (63) and Justin Upton (62) are third and fourth.

Freeman’s fifth homer of the season and his RBI single both came on eight-pitch at-bats, and the Braves appeared to have Clippard on the ropes when the right-hander hit each of the next two batters after Freeman in the seventh.

“Bases loaded with less than two (outs), that’s a great situation,” Freeman said. “But we just weren’t able to come through tonight.”

Freeman hit a towering home run to start the second inning on a 97-mph, full-count fastball from Strasburg, whose velocity began to dip immediately thereafter. Strasburg retired the last three batters in the inning, two by strikeout, but could be seen wincing and rolling his shoulders in apparent discomfort between pitches.

He was replaced after the inning and didn’t look pleased by the move. A month ago, Strasburg was slowed by biceps tendinitis, but the hard-throwing right-hander shook that off and was 2-1 with a 0.96 ERA in his past four starts before Friday, with 27 strikeouts and no homers allowed in 28 innings.

Whiled Nationals fans stressed about Strasburg, in came Stammen (3-1). He retired 12 consecutive batters to reduce his ERA to 2.04 in 14 career games against the Braves, including two starts. Though he hasn’t started a game in the majors since 2010, or the minors since 2011, you wouldn’t have known from watching him throttle the Braves for four innings.

“We swung at pitches out of the strike zone early against him, and we just get anything going against him,” Gonzalez said. “As a hitter, it’s tough to bear down on one guy because you get a different guy. You’re all geared up to face Strasburg and he goes out after seven hitters and now you’ve got to face a guy out of the bullpen.”

Teheran (3-2) was charged with seven hits, one walk and three runs, the fifth consecutive quality start for the rookie. But the Nationals scored a run in each of the first two innings, taking a 2-0 lead on a fielder’s-choice grounder that followed consecutive 10-hop (or thereabouts) singles through the right side of the infield in the second inning.

The Nationals added a run in the sixth that was a duplicate of their first-inning run. Each time, Denard Span led off with a triple and scored on Steve Lombardozzi’s sacrifice fly. The second one moved the Nationals’ lead back to two, 3-1.

“I thought Teheran pitched a great game, I really did,” Gonzalez said. “Two triples to Span, and they did a nice job situational hitting. Other than that, the other run was a couple of infield singles or balls that got through the infield. Three runs, it’s a nice outing for him. We just couldn’t get that blooper or that ball through the infield like we did (Thursday).”

Stammen left after the sixth, and the Braves went to work against erratic Clippard in the seventh. But with a chance to take a big lead, or at least tie the score, the whiff-prone Braves did the only thing they couldn’t afford to do with bases loaded and one out: strike out in consecutive at-bats.

Strasburg is 3-4 in 10 starts against the Braves, with a 3.55 ERA and 48 hits allowed 50 2/3 innings. He’s lasted 5 1/3 or fewer innings in half of those games and has one win and a 5.24 ERA in five starts at Turner Field, including games in which he lasted five, three and two innings.