WASHINGTON — The first two career starts were a struggle for rookie right-hander Jack Kochanowicz, as evidenced by his unsightly 14.14 ERA.

But Kochanowicz turned it around with a strong showing against the Nationals on Sunday, hurling 7 2/3 strong innings to pick up his first career win in the Angels’ 6-4 victory at Nationals Park. Kochanowicz, who was called up from Double-A on Saturday to make the start because the Angels had a doubleheader on Wednesday that altered their rotation, allowed just two runs on six hits and a walk with two strikeouts. He was aiming for a shutout, but gave up a solo homer to Jacob Young to open the eighth.

Kochanowicz, though, was thrilled with his performance — and he was even more excited because he had his family and close friends at the game. He grew up outside of Philadelphia, so they were able to make it to his spot start on short notice.

“I was just out there and felt more comfortable,” Kochanowicz said. “It’s the same stuff. I just have to trust myself and feel more comfortable as it goes.”

Kochanowicz, ranked as the club’s No. 9 prospect by MLB Pipeline, relied heavily on his sinker, throwing it 69 times out of his 93 pitches. It averaged 95.5 mph and helped him generate nine outs via grounders. He also mixed in 22 curveballs and just two changeups.

“It was part of the game plan, but that’s definitely my strength,” he said of his power sinker. “And when that’s working, why shy away from it? It’s just trusting it.”

He was incredibly efficient, as he entered the eighth having thrown just 72 pitches. But after giving up a homer to Young on a hanging 1-2 curveball, he allowed Nasim Nuñez to reach on an infield single before going to second base on a wild pitch.

Manager Ron Washington went to the mound, but left him in the game — until Kochanowicz surrendered an RBI single to Luis García Jr. on a 3-1 sinker and was removed in favor of reliever Mike Baumann, who walked two but got out of the jam.

Washington said he was hopeful Kochanowicz could get through the eighth, but was still plenty satisfied with his performance.

“He was getting his sinker down,” Washington said. “It wasn’t landing directly in the middle of the plate, up. He did a really good job. And more than anything else, he was calm.”

Kochanowicz’s performance helped a beleaguered bullpen, as the Angels played a doubleheader at Yankee Stadium on Wednesday and then couldn’t hold leads in the first two games of the series with the Nats — both of which ended in extra-inning losses.

The 6-foot-7, 228-pounder had trouble locating his pitches in his first two starts, leaving the ball up too often and getting punished for it. He went a combined seven innings in those two outings, but topped that total with his impressive showing against Washington.

“Jack had a really good day today,” said catcher Matt Thaiss, who was 2-for-2 with three walks. “His first couple times up here didn’t go as he planned, but you saw a glimpse of what he could be today. He pounded at the zone with the sinker, his offspeed is only going to continue to get better, and he looked a lot more mature than a 23-year-old out there.”

Kochanowicz had a 4.50 ERA in 18 starts with Double-A Rocket City this year and his last start came back on Aug. 2, when he went seven innings but gave up three runs in a loss to Biloxi. But with the Angels short on options for a starter on Sunday, they went with Kochanowicz — and he delivered.

He was backed by a five-run fourth inning against lefty MacKenzie Gore, with the Angels getting helped by a crucial error by third baseman José Tena on a hard-hit grounder from Jo Adell that could’ve been a double play. Kevin Pillar capitalized with a three-run double down the left-field line that proved to be the game’s biggest hit.

Pillar’s double was their only hit with runners in scoring position, as they walked 13 times but went 1-for-13 in those key situations.

Ben Joyce got into trouble in the ninth, allowing three hits, two walks and two runs, but sealed the deal with a double play to give Kochanowicz the victory. It also led to the customary clubhouse beer shower, rained down upon the rookie by his teammates after the game to celebrate his first career win.

“It was fun — that’s a word for it — but cold is another word for it,” Kochanowicz said. “But it was the best.”