Mariano Rivera experienced what was described as a “freak accident” leading to his injury during the Yankees Old Timer’s Day game, as explained by Andy Pettitte on WFAN Saturday.

At the time, it wasn’t immediately clear how Rivera ended up injured, but Pettitte said that it happened during a fly ball. 

Rivera tore his Achilles during the alumni game, his agent told reporters, and the Baseball Hall of Famer will have surgery next week.

“It was just a freak accident,” Pettitte remarked during the WFAN broadcast of the Yankees-Astros game on Saturday. “It involved a fly ball, and he kind of made a sudden move to go for it. As soon as he did, he mentioned feeling a pop. Horrible. I was sweating when I went in there. He was in pain, so it’s definitely a difficult injury.

“But he was alright. He was alright. Thank God it wasn’t too serious.”

A video on social media posted on Sunday appeared to show the moment Pettitte had described on radio when Rivera was playing in center field, which came in the half-inning after he legged out a single in the game.

It would be the second time Rivera suffered a serious leg injury while in the outfield. He was shagging fly balls before a May 2012 game and tore his ACL, costing him the rest of that season.

Another Yankees legend, Roger Clemens, had broken the news of Saturday’s injury on the radio broadcast of the Yankees’ 5-4 win over the Astros. 

“It was a fun day until we just heard about Mariano,” he said. “Mariano hurt his Achilles.”

Adding later: “We all thought it was a hamstring. But I think it’s a little worse than that.”

There had been plenty of excitement before the alumni game and Yankees manager Aaron Boone liked that the team had brought it back. 

“It’s something that makes our Old-Timers’ Day unique,” Boone said. “Seeing these guys out there, seeing your heroes that are well past their prime going out and still flashing a little bit, that makes for a cool thing.”

Saturday was the first time the game had been held since 2019, in part over concerns about injury.