'Doctor Who' companions team up to save world

Doctor Who's fourth season will reportedly feature an episode in which three former and current companions will join forces to save the TIme Lord.

According to The Sun, Rose (Billie Piper), Martha (Freema Agyeman) and Donna (Catherine Tate) will seek to fend off an alien invasion together with the help of the Tardis - but minus The Doctor.

An insider told the tabloid: "The chemistry between the three assistants is electric. It is so strong that we realised The Doctor could be in danger of getting in the way. So it is left to the girls to sort things out, having to save civilisation and The Doctor himself."

An episode in each of the past two seasons has barely featured The Doctor, in order to ease the filming schedule for David Tennant. Earlier this year, Blink featured a new heroine called Sally Sparrow investigating sinister statues, while Peter Kay starred as the Absorbaloff in 2006 episode Love And Monsters - with only a brief appearance by The Doctor in both stories.