President Trump hit the links with one of his biggest athlete supporters on Monday ... golfing with PGA pro John Daly!!
... and just by looking at Daly's patriotic pants, you can tell the dude was stoked to crush some balls with POTUS.
The duo met up at Trump National Golf Club in Bedminster, NJ ... and Daly -- a HUGE Trump supporter -- is calling it "one of the greatest days of my life!"
Trump clearly enjoyed the meet-up as well ... tweeting out praise to the golfer, saying "Thank you John, you are a special guy!