Ali Krieger All Smiles At Celtics-Knicks Game Despite Messy Split W/ Ashlyn Harris

It seems Ali Krieger is doin' just fine after her highly publicized split with Ashyln Harris ... 'cause the soccer star was spotted smiling ear to ear at the Knicks game Wednesday.

The Gotham FC defender was sitting courtside at Madison Square Garden to watch NY's season opener against the Celtics ... and despite everything that's going on with her, Harris, and Harris' new lover, Sophia Bush, Krieger appeared to be happy as a clam.

She had seats next to celeb makeup artist Alexandria Gilleo, and at one point, the ladies filmed themselves having an absolute blast.

Of course, things were obviously not always this way for Krieger ... especially in the last few weeks.

As we reported, Krieger was hit with divorce papers from Harris last month ... before Harris quickly jumped into a relationship with Bush.

Krieger looked to be quite bitter over it all, using a Beyoncé "Lemonade" Instagram post to imply that she had been cheated on.

The 39-year-old, though, is showing signs of moving on -- with her mind clearly now more focused on rubbin' elbows with Whoopi Goldberg than on Harris' new 'ship.

Several other stars, meanwhile, were out courtside for the game as well ... Chris Rock and Michael J. Fox sat just feet away from Krieger at MSG.

Carmelo Anthony and his son, high school hoops star, Kiyan, made an appearance too ... as did Latrell Sprewell, who played for New York from 1999 to 2003.

New England Patriots owner Robert Kraft, Yankees star Aaron Judge, Fat Joe, Lindsey Vonn and Skylar Astin also showed up for the big rivalry game.