Celine Dion Rocks Out at Lady Gaga's Las Vegas Enigma Residency Show

Celine Dion played the air guitar, sang along and clapped her hands for Lady Gaga during the "Bad Romance" singer's second show of her Las Vegas residency.

Dion -- who has had a residency of her own for years -- had one of the best seats in the house Sunday night for Gaga's Enigma show at the Park Theatre in the Park MGM Resort. Celine totally jams out to "You and I" ... even encouraging the crowd to let loose too.

Lady Gaga's residency began on Friday night, and reviews have been excellent -- with many calling the show very energetic and theatrical -- though nothing was more theatrical than Dion's dance moves.