HOUSTON – As they prepare to defend their American League pennant in the playoffs later this month, the Astros must face the reality of not having ace pitcher Justin Verlander for the postseason. And likely much beyond that.

Verlander, the reigning AL Cy Young Award winner, announced via his Instagram account on Saturday that he has decided to undergo season-ending Tommy John surgery -- the first time in his long and accomplished career that he has needed the procedure. Verlander, who has not pitched since Opening Day in July, said he consulted with several doctors before reaching his decision.

“I was hopeful that I would be able to return to competition in 2020,” wrote Verlander, “however, during my simulated game, unfortunately the injury worsened. Obviously, I’m extremely disappointed, but I will not let this slow down my aspirations for my career. I will approach this rehab the only way I know, attack and don’t look back.”

“I’m confident that with a proper rehabilitation program and my unwavering commitment that this surgery will ultimately lengthen my career as opposed to shorten it,” Verlander continued. “I can’t thank my teammates, coaches, the front office and my fans enough for the support they have given me so far in this process. I’m eager to get through this recovery and back on the field to continue to do what I love.”

Verlander started on Opening Day on July 24 and pitched well but was diagnosed with a forearm strain two days later and shut down. He rehabbed throughout the summer with the goal of returning and contributing in October. The Astros were hopeful he would throw a simulated game Wednesday and then start Monday against the Mariners in Seattle.

Those hopes were dashed after Verlander left his simulated start at Minute Maid Park after feeling something in his elbow. An MRI performed Thursday showed “differences from what we saw in July and changed the prognosis and diagnosis,” general manager James Click said. The consensus from doctors was a torn ulnar collateral ligament, which means Tommy John surgery and a 12-14-month recovery

“First of all, you can't replace Justin Verlander. No one person can replace Justin Verlander,” Click said. “This is going to have to be the total team effort, and if everybody steps up a little bit, your No. 2 starter steps into a No. 1, the No. 3 into a No. 2 and down the line, we can try to cover that a little bit. It’s part of why we’re so excited about the young arms we’ve got.”

The Astros will now rely on Zack Greinke, acquired by the club at the Trade Deadline last year, to be their No. 1 pitcher in the playoffs, with Lance McCullers Jr., Jose Urquidy, Framber Valdez and Cristian Javier in the rotation mix, as well. That’s a far cry from last year when the Astros went into October with Verlander and Gerrit Cole, who finished 1-2 in the AL Cy Young race in ’19. Houston lost to the Nationals in Game 7 of the World Series last October.

“He gave it his best effort,” said Astros manager Dusty Baker, who spoke to Verlander for 15 minutes earlier Saturday. “This guy tried to come back big time and put in a lot of hours trying to come back and help this team.”

Verlander will now attempt to become the 10th known pitcher to come back from Tommy John surgery after undergoing the procedure at 37 years of age or older. The typical recovery time is about a year, which means there’s a chance he’s thrown his final pitch for the Astros, considering he’ll likely miss all of the 2021 season and will be a free agent heading into ’22. Verlander signed a two-year, $66 million contract extension with the Astros prior to the ’19 season that was set to keep him in Houston through ’21.

“Our focus right now is making sure that, you know, he gets through the surgery and gets the procedure and gets his rehab on track,” Click said.

Verlander enjoyed one of the best seasons of his career in 2019 en route to his second career AL Cy Young Award, making 34 starts and going 21-6 with a 2.58 ERA, 300 strikeouts and a 0.80 WHIP in 223 innings. The Astros occupied the AL’s sixth postseason seed entering play on Saturday with a record of 25-26, and were three games clear of the Mariners for the AL West’s second guaranteed playoff spot.

“It’s unfortunate news,” shortstop Carlos Correa said. “It definitely sucks not having your ace moving forward, but I believe in every single guy in this clubhouse.”

Since joining the Astros in a blockbuster deal in the Trade Deadline in 2017, Verlander has taken his career to new heights. After finishing second in the AL Cy Young Award vote in ’18, he threw his third career no-hitter last year and reached 3,000 career strikeouts, while also whiffing 300 in a season for the first time.

He said earlier this year he wanted to pitch until he was 45, and perhaps take a shot at 300 career wins, but he will have to chase those goals despite having made just one start in the 2020-21 seasons.