Colin Farrell has admitted he felt ''completely ridiculous'' rehearsing for the Harry Potter spin-off.

The 40-year-old Dubliner, who plays Percival Graves in Fantastic Beasts and Where to Find Them, says it took him some time before he got used to using the prop.

'It's great to do research, but it's hard to do research on wizards.

''You can only twirl your wand in your hotel room for three or four minutes before you feel completely ridiculous, Farrell told Sci-Fi Now magazine.

Farrell's character is in charge of the protection of wizards

Eddie Redmayne, who plays eccentric wizard Newt Scamander in the fantasy film, recently said that Colin Farrell had to calm his nerves at his first Comic Con appearance with a soothing back rub.

The Oscar-winning actor admitted that he was so nervous about appearing in front of the festival's massive crowd that he needed some reassurance, and luckily Farrell had his back.

Redmayne plays eccentric wizard Newt Scamander in Fantastic Beasts

Speaking on The Graham Norton Show, Redmayne joked that he felt like "a wannabe Justin Bieber" after speaking in front of thousands of fans at the comic festival in July.

"I'd heard from friends what the experience was, but I had no idea how big it would be.

"I was chronically nervous to the extent that I had Colin Farrell giving me a back rub and whispering sweet nothings into my ear trying to calm me down," he added.

Fantastic Beasts and Where to Find Them hits Irish shores on November 18.

For a chance to win a pair of tickets to the Irish premiere screening on November 15, click here.

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