Ariana Grande’s ‘Victorious’ Costars Support Her on ‘Eternal Sunshine’ Tour

Ariana Grande‘s concert on her “Eternal Sunshine” tour is bringing out tons of winners … because a couple of “Victorious” cast members came out to show their love for the star.

The pop star rocked the Kia Forum in Inglewood, California Wednesday night … and standing in the VIP section were a pair of her former costars on the hit Nickelodeon show … Elizabeth Gillies and Matt Bennett.

Check out the clip … the Hollywood Arts High alumni are rocking out to one of Ariana’s tracks … belting out the lyrics along with their longtime pal.

Ariana, Elizabeth and Matt have known each other for nearly 20 years … having met while shooting the first season of the show in late 2009.

All three cast members are credited for each of the show’s 57 episodes … and Matt even played a love interest to Ariana’s character of sorts … with the pair sharing a couple of onscreen smooches.

This is just the first of Ariana’s three shows in Inglewood — she returns to the stage Friday and Saturday night — plenty of time for Victoria Justice and other cast members to reunite with the star before she leaves for Austin, Texas.