Sydney Sweeney Sits Courtside At Nets Game With 'Housemaid' Costar

Sydney Sweeney ditched her fiancé for a special plus-one at the Brooklyn Nets game on Tuesday ... catching all the action courtside with her 11-year-old movie costar.

The 27-year-old actress hit up the Barclays Center to watch the Nets' Battle of the Boroughs with the New York Knicks ... which ultimately ended with Karl-Anthony Towns and Co. coming away with the 99-95 victory.

Sweeney's partner, Jonathan Davino, was nowhere to be seen -- instead, she elected to have fellow "The Housemaid" cast member Indiana Elle join in on the fun.

She also opted for a more laid-back look after hitting the town Sunday night in an all-white 'fit for a date night with Davino ... rocking a black leather jacket with a pair of jeans for the NBA festivities.

Sweeney wasn't the only big name in attendance for the matchup -- Ben Stiller made the trip across the Brooklyn Bridge to catch his beloved Knicks in action, putting his fandom on full display when his squad took a five-point lead late in the contest.

Sweeney's supporters will have to wait until the end of the year to catch the flick ... but we take it they'll be thrilled to see her out with her new friend in the meantime.