John Barrowman will replace Nigel Lythgoe on the So You Think You Can Dance judging panel this weekend.
The Torchwood actor will fill in for Lythgoe, who is currently busy launching the US version of the show and exec-producing the final of American Idol.
Lythgoe had always agreed with the BBC that he would be unable to make this live show due to his commitments in the US. However, he will return from the quarter-finals onwards on May 28. Arlene Phillips will step up to become the Head Judge, while Barrowman will take on her "Queen of Mean" title.
Barrowman said: "This is such an amazing opportunity. I met all these guys when I was a guest judge at the Choreography Camp rounds a few months back, and I can't wait to come back and see how they have improved and developed as performers."
Lythgoe apologised for his absence, commenting: "It is a great shame that I can't be there to see our top ten dancers perform this weekend due to my commitments to Idol, but I will be watching them dance for their lives from LA. I have no doubt John will bring his incredible pedigree to the panel and keep the dancers on their toes.
"It's going to be great now it's down to the top ten dancers - the competition is getting hotter."
So You Think You Can Dance airs on Saturday at 5.35pm on BBC One.