Matthew McConaughey. Picture: Reuters

Matthew McConaughey thinks 'How to Lose a Guy in 10 Days' is the worst rom-com he's ever made.

The Oscar-winning actor - who has starred in a string of rom-coms during his career, including 'The Wedding Planner', 'Failure to Launch' and 'Ghosts of Girlfriends Past' - has admitted that the 2003 movie is the bottom of the list of rom-coms he's made.

Asked to reveal his own list of his worst rom-com movies, Matthew said: "Let's go 'How to Lose a Guy' ... then let's go 'Failure to Launch' then 'The Wedding Planner'."

'How to Lose a Guy in 10 Days' - which was based on a cartoon book of the same name by Michele Alexander and Jeannie Long - was actually a significant box-office success.

And even though he didn't like the movie, Matthew admitted it continues to reward him.

He told 'Watch What Happens Live with Andy Cohen': "'So How to Lose a Guy' ... that film has been my greatest mailbox money of any film.

"It is always on and there's always this great little cheque that shows up in the mail from 'How to Lose a Guy in 10 Days'. I did that however many years ago!"

Meanwhile, Matthew recently claimed that Anne Hathaway is one of his few true friends in the movie business.

Matthew, 49, reunited with Anne to star in the Steven Knight-directed thriller 'Serenity', having previously worked with her on 'Interstellar'.

He said: "For me, this business and relations at work are transitory.

"By design you're closer with most people at the time when you're working because it's intense. You're working together and then you go on a press tour and you're around each other and you're with each other's families and then, poof, you go away. And I don't have that many relationships that I maintain. 

"Anne and I don't call each other every week, (but) we do still keep in touch."