Adam Lambert and Demi Lovato have collaborated on a new Glee song.

Two new tracks due to premiere on the show on Tuesday (March 4) in the US have emerged online.

One sees Lambert, Lovato and the Glee cast take on 'The Happening' by The Supremes.

The other tune features Lambert alongside the cast as they try Heart's 'Barracuda'.

The songs will feature on the episode 'Trio', which sees Lambert resume his role as Elliott 'Starchild' Gilbert and Lovato play the part of Dani.

Lambert's rep meanwhile confirmed last year that the singer's role in Glee will only be as a guest as a result of his busy 2014 schedule.