Mel Gibson struggled to improvise in 'Daddy's Home 2'.

Mel Gibson

Mel Gibson

The 61-year-old actor - who portrays Mark Wahlberg's on-screen father Dusty in the production - has admitted he felt "lost" and "left behind" when director Sean Anders encouraged the cast to go off script when filming the comedy film.

Speaking to New! magazine, the movie legend said: "I was lost. They left me behind. I felt like a spectator at a Beijing Ping Pong match with the flip-flapping back and forth between them that I was trying to keep up with.

"It was a job because they both have these insane, off-the-wall minds where they store these streams of consciousness."

And Mark, 46, believes it was his off the cuff and quick exchanges with co-star Will Ferrell that intimidated Mel and caused him to doubt his own acting ability.

The 'The Fighter' hunk said: "Will and I, we'll shoot what's on the page and then start improvising and we start going absolutely crazy and Mel was a little taken by that, like, 'Oh my God, what is happening here, are they expecting me to do this?'"

But the 'Hacksaw Ridge' star soon got the hang of the witty entendre, and ended up having "more fun" than anyone else on set because of the freedom to stray away from the script in a "safe environment".

Mark continued: "As soon as he realised what the gag was, he'd jump right in and I think he had more fun than everybody. It was just one of those things where we just kind of go for it and it's a safe environment to go crazy and risk looking ridiculous and know that you'll be taken care of."