Caitlin Clark turned a brutal double-duty night into a headline-grabbing moment off the court ... linking up with Morgan Wallen during his second Indianapolis show, just hours after a gut-punch loss.

Clark had just finished a tight matchup against the Dallas Wings, where her team came up short by just three points in a game that stayed close down to the final minutes. However, instead of heading straight into a quiet postgame night, she later made her way to Wallen’s sold-out concert stop in Indianapolis.

The "I Got Better" country singer -- who was in town for night two of his "Still The Problem Tour" stop -- surprised the crowd when Clark walked out alongside him ... sending the arena into a frenzy.

The moment instantly shifted from country concert to crossover spectacle ... with fans realizing they were watching one of Indiana’s biggest sports stars share the spotlight with one of country music’s biggest names.

Clark, who has quickly become a face of women’s basketball and a major draw in every arena she enters, appeared in good spirits despite the earlier loss ... smiling and engaging with the crowd as Wallen welcomed her onstage.