Jordan Spieth -- Calls Out Dirk Nowitzki ... Let's Foursome!

He's already got a green jacket ... now Jordan Spieth is looking to make another dream come true -- dude wants to golf with Dirk Nowitzki.
Turns out the 21-year-old is from Dallas and happens to be a big fan of the big fella -- and when TMZ asked if he could golf with any celeb in the world, the first name that came to mind was Dirk.
Good news for Jordan ...