Rachel McAdams ''practiced'' her boxing skills on the set of 'Southpaw'.

The 36-year-old beauty stars as Maureen, the wife of boxer Billy ''The Great'' Hope, in the movie and has revealed she used her time on set to perfect her boxing techniques.

She shared to USA Today: ''I figured Maureen would understand boxing really well. She'd make it her business to know it. Jake [Gyllenhaal] came and watched me box in the ring.

''I practiced. I wasn't fighting. I definitely wasn't fighting. I just tried to pick it up. Nowhere near the extent that Jake did. It was an excuse to sweat and get in shape. It's a total head to toe workout. You do one three-minute round and you're toast.''

And her co-star Jake, 34, has admitted he was terrified about looking like an ''idiot'' in the movie but says the fear motivated him.

He said: ''I spent five months training for the movie and I trained twice a day. I figured I'd make five months into 10 months if I did that.

''And I was just basically scared that I'd look like an idiot, so I worked as hard as I could. Fear is sometimes a good motivating thing.''