Allison William is a sword fighting star

Allison Williams has been practicing sword fighting with a kitchen knife.

The 26-year-old actress is best known for playing straight-laced Marnie on TV show Girls, but her next role is something very different. She's portraying Peter Pan in a live musical which will air on NBC in December and has been taking training pretty seriously.

"The sword fighting has been such a fun process for me. I practice in my kitchen with a kitchen knife," she told New York Daily News.

Allison is happy to do whatever it takes to make the performance believable. At one point she thought she'd have to cut her long hair, even checking that would be OK with those involved in Girls.

"I was all ready to cut off my hair and [Girls producer and co-star] Lena [Dunham] even OK’d it!” she laughed.

Rehearsals for the show have started and Allison is having great fun. Many have wondered how she'll manage to portray a boy as she is so feminine in her Marnie guise, but Allison assures she has all bases covered.

"It’s not nearly as hard as it sounds," she explained. "I wear exercise clothes all day, every day. I put on brown boots and I stomp around like a boy and learn all of these new tricks."

During the performance the actress will be seen soaring through the air, which she's very excited about. Her co-stars include Christopher Walken, who will appear as iconic Captain Hook, and Christian Borle, and they have both helped her get in character.

"I see examples of boyish behaviour all around me," she explained. "I’m pretty mischievous, and being able to let that mischief run the show is really liberating."