James McAvoy's performance in Filth is better than Robert De Niro in Taxi Driver according to author Irvine Welsh.
Another of Welsh's novels has been adapted for the big screen after the success of Trainspotting back in 1996.
McAvoy takes on the role of Bruce Robertson in the movie and Welsh was incredibly impressed by his performance.
Speaking to The Press Association the writer said: "He is absolutely amazing. It's just one of the greatest acting performances I have ever seen.
"I think he's better than Robert De Niro in Taxi Driver. He is absolutely electric and is right into the character.
"It's a fantastic emotional performance."
Filth is directed by Jon S. Baird, who also adapted Welsh's novel. Jamie Bell, Imogen Poots an Jim Broadbent are also all one the cast list.
Filth will be released next year.