Patrick Mahomes doesn't need many pep talks for big games these days -- he is, after all, going for his fourth championship this weekend -- but if he wants one from Dad ... Patrick Mahomes Sr. is giving TMZ Sports a sneak peek into what his message will be!

The elder Mahomes told us on Friday out in New Orleans that if his Chiefs star son leans on him for advice heading into Sunday's tilt with the Philadelphia Eagles ... his note will be simple.

"Players make plays," he said.

The memo shouldn't be too hard to follow ... the 29-year-old quarterback has answered the bell in nearly every big moment that Kansas City's had over the last seven years.

In fact, if he wins Sunday -- some are already saying they'll give him the G.O.A.T. crown ... although Mahomes Sr. wasn't ready to entertain that talk just yet.

As for how he's feeling about his son's chances heading into his fifth Super Bowl ... Pops said they're not treating it any differently than other games -- and they're hopeful Patrick will "come out there and have a great game on Sunday and hopefully we get a W."