Bob Costas was left saying "Sorry" while working the Yankees vs. Guardians game ... after he accidentally called Cleveland pitcher Shane Bieber "Justin Bieber" -- and the moment is hysterical.
The legendary broadcaster made the mistake during the top of the 6th inning of Game 2 of the American League Division Series on Friday ... when he meant to talk about the 2020 Cy Young winner, but ended up name-dropping the pop star.
"Justin Bieber just threw his 84th pitch," Costas said before immediately realizing his mistake. "Did I actually call Shane Bieber 'Justin Bieber?' I vowed that would not happen."
Costas hilariously defended himself ... saying, "I'm sure that's not the first time that's happened in his life."
MLB's Shane Bieber Says Justin Bieber Shout-out Was Life Milestone
In fact, it's not -- Topps accidentally put Justin's name on Shane's trading card back in 2019 ... which led J. Biebs to shout out the pitcher on Twitter.
TMZ Sports even talked to Shane about the Justin confusion shortly after it happened ... and he said it was just "a matter of time" before someone made the mistake -- and he was right, thanks to Costas.
JB and SB have been tied to each other since ... and the "Honest" singer even has his very own "Not Shane Bieber" jersey.
"I wonder if [Justin's] watching the game," Costas joked.