Jennifer Lopez Hilariously Fast Dances to Undanceable '70s Slow Jams -- Watch

Jennifer Lopez Tonight Show

The 'El Anillo' singer appeared on Wednesday's episode of 'The Tonight Show Starring Jimmy Fallon.'

Jennifer Lopez is one of the hardest working women in the industry, and on Wednesday's The Tonight Show Starring Jimmy Fallon, she proved it. The 48-year-old entertainer and Fallon competed against each other to see who could better "fast dance" to slow songs from the '70s.

All picked by The Roots' Questlove, the two took turns busting moves to the least danceable jams with the best fastest dancer winning. Dressed in a body-hugging red gown with sequins and a thigh-high slit, J.Lo took the stage first and danced to "Three Times a Lady" by Commodores and then to Richard Harris' "MacArthur Park."

On his end, Fallon shimmied to "Babe" by Styx. Naturally, the World of Dance judge proved that no matter what song was chosen, she couldn't be bested!

Watch the epic dance-off below, which also featured a hilarious duet.

ET caught up with Lopez and her boyfriend, Alex Rodriguez, at Monday's glamorous Met Gala, where they dished about their time together since their public debut.

Rodriguez called the year “awesome,” while Lopez agreed, saying it had been an “amazing year.”

Watch the video below to hear more of what they shared.