The new season of `Downton Abbey`, which is set to go live, will see Hollywood star George Clooney kissing Dame Maggie Smith.

The veteran actress plays the Countess of Grantham in ITV's period drama, and has filmed scenes with Clooney for a special Text Santa mini-episode.

Usually dignified, the Countess won't be able to stop herself from fainting in a "comedy fall" when Clooney gives her a kiss in the episode, according to fellow cast member Laura Carmichael.

"There is a very brilliant moment with Maggie and George - and I don't know if I want to give away more than that really - but Maggie does a comedy fall,` femalefirst.co.uk quoted Laura as saying.

"George plants a kiss and Maggie ends up on the floor, it's wonderful. He was hilarious."

The special one-off episode airs later in the year.