The busty blonde will perform Britney's breakthrough hit ...
In the clip, Upton pounces on the ground, seductively crawling toward the camera before leaping up to show off her curves. She completed her risqué getup with a barely-there black skirt and thigh-high stockings. Even co-host Chrissy Teigen looks stunned. She seems pretty accurate with the choreography.
Ricky Martin also appeared on the show - which is due to go out on Thursday - but based on this clip, all eyes were on Kate.
She captioned the video: "Morning workout with my new favorite sweatshirt I took from @yutsai88 #modelsmodelsmodels #gymchella @benbrunotraining".
Russia vetoes UN resolution to condemn Syria chemical attack
He said the two sides would also discuss disagreements on Syria and how to end the country's six-year civil war. The jet dropped sarin on the western Syrian village of Khan Sheikhoun, killing at least 70 civilians.
Kate Upton is in full Britney-mode for her "Lip Sync Battle" debut.
"There's no sex before a game - absolutely none".
At this rate, the next season of Lip Sync Battle will be on Cinemax at 3 am.
The episode of Lip Sync Battle airs April 20 on SPIKE at 10 p.m. EST.