Derek Jeter, Hannah Date Night At Heat Game Just 2.5 Wks After Son's Birth

Derek Jeter's on full-time daddy duty, but that didn't stop him from catching some playoff basketball, pulling up to Game 4 of the Heat vs. Celtics series in Miami with his wife Hannah ... just 18 days after their son was born!

And, HJ looks amazing!

Cameras captured The Captain throughout the evening ... as he chatted with his wife as the Celtics looked to avoid the sweep at the hands of Jimmy Butler's Heat squad.

Of course, DJ and Hannah -- who got married in 2016 -- have been on cloud nine since announcing their son, Kaius Green Jeter, was born on May 5.

The couple now has 4 kids.

Derek and Hannah weren't the only celeb in the building ... PGA Champion Brooks Koepka, actor Jeremy Piven, and Minnesota Timberwolves star Anthony Edwards were there, too.

Derek's former Yankees teammate, Alex Rodriguez, a minority owner with the T-Wolves, was also at the game.

What's interesting ... no NBA team has ever come back from a 3-0 series deficit, but it has happened in baseball.

Ear muffs, Yankees fans.

Jeter and A-Rod starred on the infamous 2004 NYY team that blew a 3-0 lead to the Boston Red Sox, the first time in MLB history.