Rachel McAdams isn't always convinced her boyfriend Michael Sheen is speaking English.

The 33-year-old actress has been dating the Welsh actor since July 2010 and the pair are often amused by the phrases they each use that are particular to their birthplaces.

She said: "Communication can be interesting because he comes out with all these wonderful British sayings, which in turn makes me come up with my own Canadian sayings.

"Sometimes I wonder if we're even speaking the same language. Some days I even say to him, 'Are you sure you're speaking English?' And he will look at me and say, 'Ahem, I think you'll notice that we invented English...' "

Rachel admits her relationship with Michael - who has 13-year-old daughter Lily with ex-girlfriend Kate Beckinsale - can be a "challenge" because of the amount of travelling they do, but they manage to make their union work.

She added to Britain's HELLO! magazine: "It can be a challenge but the nature of our job is living like a gypsy, so we're more or less used to it by now.

"It keeps life interesting and exciting and you get to see the world. But for me, I don't like to do two jobs back to back. I like to have time in between jobs to go home to Toronto to unwind and reconnect with family and friends. That's very important to me."