Lionel Richie Hospitalized

Lionel Richie is hospitalized in the intensive care unit in St. Louis after performing in the city over the weekend ... TMZ has learned.

Sources with direct knowledge tell TMZ ... Lionel checked himself into a local hospital after his Saturday night performance at The Muny in Forest Park to have some tests run.

We're told Lionel is being cautious and doctors are looking into possible slight dehydration. Our sources say he's hoping to be discharged Tuesday.