Vick explained ... when he was battling through ailments during big games in his legendary career, it made him focus more on the field -- and, in turn, upped his game a bit.

The former Philadelphia Eagles signal-caller tells us he expects similar results from Mahomes in the AFC Championship Game on Sunday.

"I know this from playing at a high level and playing against high-level competition," Vick said, "sometimes when you play hurt, you'll be a little bit more focused. A little bit more dialed in."

Mahomes injured his ankle last Saturday against the Jacksonville Jaguars, but finished out the game. Vick says the Chiefs' star's ability to come back despite twisting the limb gives him confidence Mahomes is one of the rare athletes who can step up despite a wound.

"Playing hurt is not a bad thing if you know how to do it," Vick said. "Only certain people can do it -- and the ones that are listening right now, they know what I'm saying. They can relate."

Mahomes hasn't been seen sporting much of a limp at all since the injury -- and is expected to go against Cincinnati.

Of course, if he wins, he'll have a spot in yet another Super Bowl -- and if the Eagles manage to do the same, Jalen Hurts will too ... marking the first-ever Big Game that will feature two Black starting quarterbacks.