Karen Gillan was hesitant about joining 'Jumanji: Welcome to the Jungle'.

The 30-year-old actress stars as Ruby Roundhouse in the sequel to the 1995 classic - which starred the late Robin Williams - and Gillan admitted she is the ''number one fan'' of the original and was worried about the sequel.

Speaking exclusively to BANG Showbiz at the UK premiere of the new Jake Kasdan-directed film at Vue Cinema, in London's Leicester Square on Thursday (07.12.17), Gillan said: ''[I got involved in the film] because I am the biggest fan of the original, ever.

''I'm gonna go ahead and say the number one fan. So when I heard that they were making a sequel to it, I was first of all like 'what are they going to do with my 'Jumanji'?'

''And then I read the script and learned it was going to be very special and then I just really wanted to be a part of it.''

Gillan stars alongside DWAYNE 'THE ROCK' JOHNSON, Kevin Hart, Jack Black and Nick Jonas in the new film, which takes a different twist to the original.

In the first movie, components of the titular game are brought into the real world but in the sequel, four teenagers are transported inside the game and become the avatars they chose to play as and have to fight their way through the jungle to escape.

Gillan said she couldn't compare the two movies because she loves ''them both so much''.

She explained: ''It's hard to compare them. The original is so brilliant but this is a movie in its own right.

''I mean, we pay homage to the original but this is a different concept so we've, you know, evolved it a little.

''So I can't really put them head to head because I love them both so much.''