The legendary NFL quarterback showed off his boy's height and his coordination in a happy birthday post Thursday ... and check it out, little Jack is all grown up!!

In a series of pics Tom threw up on his Instagram page to commemorate Jack's 17th trip around the sun, you can see he's now eye-to-eye with his 6-foot-4 father. He's got a helluva golf swing, too. And, according Tom, he's winning pickup basketball games as well.

"Happy 17th birthday to the kindest, sweetest, most thoughtful 17-year-old, I know," said Brady, who shares Jack with his ex, Bridget Moynahan. "You are truly a blessing in my life and I am so grateful to watch you mature into a young man. Your love of family, friends, school, athletics, hard work and dedication to everything you put your energy into are just some of your amazing qualities."

"I love spending every minute with you and I cherish our time together. (Those are all my favorite things about you. My least favorite is that you can beat me in one on one now 🙄😂)."

Tom went on to say he'll love his boy "always and forever."

Brady's no stranger to boasting about his kid's athletic abilities -- just a year ago, he showed off Jack's smooth jumper. And, when he was still playing with the Bucs back in 2022, he actually let Jack get under center during a Tampa Bay workout.