HOUSTON — Not the best of starts. For Felix Hernandez or the Mariners.

Hernandez lasted just five innings Monday night in the season opener against the Houston Astros at Minute Maid Park before exiting because of tightness in his groin.

Before he left, the King served up two booming homers in a 3-0 loss.

Actually, other than those blasts by George Springer in the first inning and Carlos Correa in the fourth, Hernandez pitched reasonably well. He struck out six, walked none and threw 45 of 65 pitches for strikes.

It just didn’t come close to matching Houston lefty Dallas Keuchel, who flashed his 2015 Cy Young form in stifling the Mariners’ revamped lineup on two hits through seven innings.

Luke Gregerson pitched out of a two-on jam with two outs in the eighth by retiring Robinson Cano on a line drive to right field. Ken Giles closed out the shutout for a save.

What wasn’t immediately known is whether the injury occurred in the fourth inning when Hernandez came up limping after breaking late from the mound on a grounder to first base.

So one game is in the books.

Springer crushed Hernandez’s fourth pitch of the season, a 92-mph fastball, high over the Crawford Boxes atop the left-field scoreboard for a leadoff homer. The 389-foot drive was a homer from the time it left the bat.

Alex Bregman followed by grounding a single up the middle and stole second when Jose Altuve swung through a full-count slider. The Mariners had a chance for a double play, but catcher Mike Zunino bounced the throw.

Hernandez ended the inning when Correa lined into a double play.

Another double play aided Hernandez in the second inning, but a catcher’s interference call on Zunino put runners at first and second with one out in the third.

Hernandez kept the deficit at one run by retiring Bregman on a fly to right before striking out Altuve.

The Mariners mounted their only real threat against Keuchel in the fourth inning when Cano grounded a one-out single to right, and Nelson Cruz followed with a walk.

It came to nothing when Kyle Seager took a third strike and, after a walk to Danny Valencia loaded the bases, Leonys Martin grounded a first-pitch fastball to second.

The Astros then boosted their lead to 2-0 when Correa opened the bottom of the inning by launching a 449-foot bomb on a 91-mph fastball. The drive somehow stayed just fair down the left-field line as it left the stadium.

Hernandez then broke late from the mound on Josh Reddick’s grounder to first base. Hernandez beat Reddick to the base for the out but came up limping.

Cano waved trainer Rick Griffin to the mound. Hernandez finished the inning and worked a one-two-three fifth before leaving the game.

The Astros then jumped reliever Nick Vincent for another run in the sixth inning. Bregman led off with a walk, went to second on Altuve’s single to left and scored on Correa’s sacrifice fly.

PLAY OF THE GAME: Keuchel won a Gold Glove in each of the last three seasons — and he showed why in making a terrific play on what appeared to be a great bunt by Segura in the third inning.

Keuchel pounced quickly on the ball and made an accurate throw to first that just beat Segura for the inning’s final out.

Proving it wasn’t a fluke, Keuchel made a similar play on a softer tapper up the third-base line for the final out in the seventh inning.

PLUS: It only counts as one loss…Segura had two hits and was robbed of a third by Keuchel in the third inning…lefty James Pazos needed just 11 pitches to retire four straight batters after entering the game with two outs in the sixth inning.

MINUS: Zunino had a rough defensive start. He bounced a throw to second in the first inning when an accurate throw would have retired the runner, and he committed catcher’s interference in the third inning…Hernandez’s suspect defensive skills came into play in the fourth inning when he broke late from the mound on a grounder and came up limping after taking the throw…

STAT PACK: Hernandez struck out six in his five innings and moved past Hall of Fame Lefty Grove and into 51st place on MLB’s all-time list with 2,269.

SHORT HOPS: Springer’s drive in the first inning was the first leadoff homer by a Houston player in a season opener since Terry Puhl in 1980 against the Dodgers.