A's Legend Barry Zito Sings National Anthem At Last Game In Oakland

Tons of Oakland Athletics legends have made the trip to Northern California for the team's swan song in the East Bay ... including former ace Barry Zito -- who was actually called upon to sing the national anthem at Thursday's finale!

The pitcher-turned-musician helped conclude the pre-game festivities at the Athletics' last-ever contest inside the Oakland Coliseum ... by belting out a sweet rendition of the Star-Spangled Banner.

The three-time All-Star -- who made the transition to music following his retirement from the sport in 2015 -- picked up the mic just before first pitch against the Rangers ... and he killed it, sending the crowd into a frenzy.

Afterward, he hopped into the broadcast booth and spoke about the moment ... as well as the last days of the "Oakland" A's.

"You can't prepare for something like this," he said. "Got a call a couple weeks ago and they asked me to come out. We had a crazy summer. My wife was in the hospital with pregnancy stuff, we just had a kid two weeks ago, all the reasons to not [come out]."

"But, she was supportive, so I came out for 24 hours and got to be a part of this."

Zito wasn't the only legend to show up for the game ... as the likes of Ricky Henderson and  Dave "Smoke" Stewart also made it for the matinee game.