PHILADELPHIA -- Jake Irvin faced the challenging top of the Major League-leading Phillies’ order head on.

Those results were strong. Kyle Schwarber and Bryce Harper: 0-for-6. J.T. Realmuto and Alec Bohm: 2-for-6.

Yet the right-hander’s third career start versus Philadelphia on Friday night at Citizens Bank Park had ups and downs. Irvin faced a total of 17 batters through three innings before locking in to retire the side in his final two frames in the Nationals’ 4-2 loss.

“[I was] pretty bad in the beginning,” said Irvin, who is 2-4 with a 3.91 ERA in nine starts. “Made some really bad pitches, and that’s the ones that those guys ended up making me pay for a little bit. After that, settled in, kind of realized the attack plan from the other side and made the adjustment, but it was a little too late.”

Irvin tossed 93 pitches (57 strikes) across five innings against the Phillies in the series opener. He allowed four runs on five hits, one walk, one wild pitch and two hit batters. Irvin also struck out two. He has issued two or fewer walks in all of his starts this season.

“That’s a tough lineup all the way through,” said manager Dave Martinez. “Once he settled down, he gave us five good innings.”

Irvin opened his first game at Citizens Bank Park by inducing a Schwarber flyout to left field. After he allowed a single to Realmuto, Irvin answered by getting Harper to pop out to third. With two outs, he gave up an RBI double to Bohm and hit Bryson Stott with a pitch before Nick Castellanos grounded out to third to end the inning.

Facing the bottom of the Phillies’ order to open the second frame, Irvin walked Brandon Marsh and surrendered a single to Edmundo Sosa. A wild pitch drove in a runner. Irvin escaped much further damage by retiring Johan Rojas (groundout), Schwarber (RBI groundout) and Realmuto (flyout) in order.

“He’s made unbelievable strides in really how to stay out of those big innings,” Martinez said of Irvin. “Things could have gotten away from him. He made some adjustments -- I know [pitching coach Jim] Hickey talked to him in between innings. His head was getting a little bit out there early, and so he started yanking pitches. He was able to settle down after that and keep us in the game.”

Irvin’s third inning began with two quick outs on a Harper flyout and a Bohm ground ball. But a bunt single to Stott was followed by a Castellanos hit-by-pitch, leading to Stott scoring on a Marsh double.

After that, neither Irvin nor the Nationals pitching staff -- including relievers Jacob Barnes and Jordan Weems -- allowed another baserunner. Irvin locked in to deliver 1-2-3 innings in the fourth and fifth.

“I think it’s just kind of settling into the rhythm of the game, and that needs to happen from pitch one,” Irvin said. “For me, it was just throwing too many heaters early, getting myself in predictable heater counts and then making bad fastball pitches. Being able to mix early, keep guys off balance from the jump is kind of the key.”

Irvin went to his curveball for nearly half his pitches (41). He induced 23 swings and seven whiffs with it. Irvin also delivered his sinker (23 pitches), four-seam fastball (22), cutter (five) and changeup (two).

“We started throwing more breaking balls at the end,” said catcher Keibert Ruiz. “He was getting ahead with those pitches and finishing, too. So I think that was key late in the innings.”

In front of a sellout crowd of 44,507 at Citizens Bank Park, Irvin improved his career matchups to holding Schwarber 0-for-8, Harper 2-for-6 and Bohm 2-for-9. He is continuing to develop as a reliable member of the Nationals’ starting rotation in his second Major League season, setting the stage for potentially many more matchups against the National League East opponent.

“It’s awesome,” Irvin said of the setting. “That’s why you grow up wanting to be a big leaguer, right? To pitch in environments like this. It’s a ton of fun. I wouldn’t want it any other way. Unfortunately, it didn’t swing our way tonight.”