John Travolta has turned down a chance to appear in the smash hit U.S television series 'Glee' because of a timing issue. 

The iconic Hollywood actor has flexed his musical capabilities in the well-loved movie 'Grease' and film adaptation of Broadway's 'Hairspray', but told Entertainment Tonight that 'Glee' won't happen:

“They’ve asked but when I do musicals I train for six to nine months... and a show like that is an on-demand thing."

“I really have a criteria or a pride that I would wanna knock ’em dead, and I don’t think I’d knock ’em dead in a week.”

Watch the 'Glee' cast perform a rendition of that classic hit from 'Grease', 'You're The One That I Want', here: