WASHINGTON -- Mitchell Parker had set the stage with his MLB debut, earning his first career win against the Dodgers -- who boast one of the most star-studded lineups in the Majors. He was asked once more to face a star-studded lineup for his home debut -- and the second start of his career -- against the Astros on Sunday afternoon.

“I’m just trying to think about it as little as I can before and take it one pitch at a time and not put too much pressure [on myself],” the 24-year-old said.

His mindset before games has worked thus far. Parker and the bullpen held the Astros in check, and the offense did the rest, figuring out how to get the bats going early in a 6-0 win over Houston at Nationals Park.

Parker, Washington's No. 21 prospect per MLB Pipeline, blanked Houston for seven innings, allowing only three hits and no walks while striking out eight to earn his second career win. He dealt 73 pitches, 57 of which were strikes. He ended his day with a 1.50 career ERA in 12 innings.

The rookie joins Shota Imanaga, Tanner Bibee, Johnny Cueto and Andy Sonnanstine as the fifth starter in AL/NL history (since 1901) to strike out at least 12 hitters and not issue a walk in the first two games of his career.

“He just pounded the zone,” said Astros outfielder Chas McCormick of Parker. “He was working fast. He has a good fastball, and he knows how to throw his offspeed for strikes. Early on, he was showing a lot of offspeed that got us a little out in front. He just knew where to throw his splitter, and when he needed to throw his fastball, he threw his fastball up and did a really good job.”

Parker got to work quickly in the first inning. He struck out the first two batters he faced -- Jose Altuve and Yordan Alvarez. He dealt to Kyle Tucker, who weakly grounded out to give him a 1-2-3 inning.

The southpaw provided the foundation for the Nats’ offense to find success in its run game and get on the board first with a 3-0 lead in the first inning.

“We see how fast he is working and what he’s doing,” Nationals manager Dave Martinez said. “They want to score for any starter, but to be able to tack on those runs early like that, it eases the starting pitcher, and I definitely think it eased Mitchell today.”

Knowing the standard he set at the beginning of the game, Parker cruised through the next six innings, remaining efficient with his pitches and trusting the defense to make plays behind him.

“He’s had an incredible start, and playing behind him, he’s thrown a lot of good innings,” said Luis García Jr. in Spanish. “We feel comfortable playing behind him, and we feel like good things will happen.”

Washington’s offense continued to back up Parker’s performance, with Joey Meneses grounding an RBI single to right field, scoring Jacob Young and CJ Abrams to extend the lead to 5-0 in the fifth inning. Nick Senzel sealed the deal in the bottom of the sixth, hitting his first home run of the season on a 2-2 pitch to bring the score to 6-0, which held up for Washington’s first home series win of the year.

The Astros were unable to find an answer to Parker’s repertoire -- consisting of his curveball/fastball combination and a splitter.

“He threw some really good split fingers,” Astros manager Joe Espada said. “The change of speeds. He had a pretty good angle. We just couldn’t get anything done.”

Parker became the first player in franchise history to throw seven or more scoreless innings on fewer than 75 pitches (since pitches were first tracked in 1988), and he is the first MLB player to do so since the Braves’ Kyle Wright, who accomplished the feat in 2022.

The Nats’ fifth-round pick in the 2020 MLB Draft was called up to take Josiah Gray’s spot in the rotation on April 13. Gray had sustained a right elbow/forearm flexor strain, shutting him down for a few weeks.

Going forward, Martinez said, the plan is to continue to build up Parker, as the club may need him to go eight or nine innings in the future. In the meantime, Parker will keep working on settling his nerves before games, regardless of the lineups he will face in the future.

“Just keep going for the next one, that’s all we’re aiming for,” he said.