Indianapolis Colts quarterback Andrew Luck stunned the NFL world late Saturday, confirming he was retiring from the sport at the age of 29.

Luck has suffered a litany of injuries throughout his career and looked set to miss the start of the 2020 season, which begins in just two weeks.

"This is the hardest decision of my life,” he told reporters at a hastily arranged news conference after the Colts’ preseason loss to the Bears.

News of Luck's retirement leaked during the game and spread quickly on social media as he stood on the sidelines of Lucas Oil Stadium.

Before he spoke, Luck was booed off the field by the Indianapolis fans who had hailed him as their hero for the last seven years.

Luck leaves the field following the Colts' preseason game against the Chicago Bears Saturday. AJ Mast / AP

“I’d be lying if I said I didn’t hear the reaction,” he said. “It hurt, I’ll be honest with you, it hurt.”

Luck entered the 2012 NFL draft as one of the most heralded prospects in history.

Fans across the league urged struggling teams to "suck for Luck" and with their own superstar and franchise QB Peyton Manning injured at the time, the Colts did just that.

They drafted Luck with the No. 1 pick and with their future seemingly set, Manning was gone.

It was a decision that seemed a no brainer almost every time Luck took the field, but making that happen ultimately became too much of a struggle.

“I’m in pain, I’m still in pain. It’s been four years of this pain, rehab cycle,” Luck said. “It’s a myriad of issues — calf strain, posterior ankle impingement, high ankle sprain. Part of my journey going forward will be figuring out how to feel better.”

The former Stanford star led the Colts to the playoffs in each of his first three seasons and to the AFC championship game after the 2014 season — without missing a start.

But a subpar offensive line struggled to keep Luck upright, with shoulder and kidney injuries keeping him sidelined or playing hurt.

Last year Luck looked like his old self, winning the league’s Comeback Player of the Year award as he set career highs in attempts (639), completions (430), and completion rate (67.3 percent).

But then came the mysterious calf-ankle injury.

So after marrying his longtime girlfriend this spring and now awaiting the birth of his first child, Luck called it quits.

Colts fans reacted with shock at Saturday's game after Adam Schefter tweeted that Luck was planning on retiring. Bobby Ellis / Getty Images

The Colts will now turn to Luck's backup, Jacoby Brissett.

“Teams win, don’t write the end of the story yet,” Colts general manager Chris Ballard said. “I’m telling you the story’s not over yet.”

Andrew Luck chose to end this chapter of his.

"I am going to retire," he said, his eyes watering.

"This is not an easy decision. It's the hardest decision of my life. But it is the right decision for me."