SEATTLE -- The Kumar Rocker Era began with pressure.

The Rangers’ No. 2 prospect, who has dealt with a career’s worth of adversity before ever stepping on a big league mound, did not flinch.

“I think this is a very mature, poised player, who knows exactly what he needs to do to be successful,” Rangers general manager Chris Young said before the game. “That happens for different players at different times, and I have no doubt that Kumar is ready for this moment.”

He showed it Thursday.

Backed into a corner to begin his Major League debut, Rocker clamped down to get the Rangers out of a jam, and went on to give Texas just about everything it could have hoped for in his four-inning start, finishing with seven strikeouts and allowing one run in a 5-4 win over the Mariners at T-Mobile Park.

Victor Robles lined Rocker’s first pitch in the bottom of the first inning back up the middle for a leadoff single. One pitch later, Julio Rodríguez sent a soft grounder through a hole in the right side of the infield -- and then proceeded to steal second, putting two Mariners in scoring position with no outs.

Then Rocker, the first player of Indian descent to appear in a Major League game, went to work.

Cal Raleigh was his first strikeout victim, looking at a 97.1 mph fastball on the inside corner. Then came Randy Arozarena, who fouled the first two two-strike offerings before swinging through Rocker’s vaunted slider. Luke Raley tagged the first pitch he saw to right field, but it went straight to Travis Jankowski, getting the rookie starter out of his first big league jam in his first big league inning.

Josh Jung gave Rocker a lead to work with in the top of the second with a solo homer, and the rookie righty let his stuff go to work soon after. Rocker retired the side in order in the second, and got out of the third with another strikeout, filling up a highlight reel with flailing swings by Mariners batters who, for the most part, just could not figure him out.

Rocker recorded 17 whiffs, the most by a Rangers pitcher in their Major League debut since pitch tracking began in 2008. Thirteen of those came against his slider -- one off the Rangers’ season high of 14, set by Jon Gray in May.

The 24-year-old’s fastball averaged 96.8 mph, topped out at 97.6, and got three whiffs of its own.

The only blemish of Rocker’s night came on the one hit he allowed after the first two batters of the game, when Justin Turner belted a solo home run to straightaway center on a full-count fastball.

With Rocker sitting on 74 pitches after a long fourth inning -- right around his pregame target -- manager Bruce Bochy went to the bullpen going into the fifth.

But in just four innings, Rocker had given the baseball world a whole lot to talk about.

“To see him be here and realize his dream and do it in a Rangers uniform, I couldn’t be happier,” Young said.