Atonement's James McAvoy and Keira Knightley
08/30/2007 AT 09:00 AM EDT
has kissed some of the biggest heartthrobs in Hollywood, but her current leading man gets top billing.
"James [McAvoy] is the best kisser ever!" a giggling Knightley, 22, said of her Atonement
costar while sitting in romantic Venice.
Despite kissing Johnny Depp
and Orlando Bloom
, Knightley – who is currently dating actor Rupert Friend – glanced at McAvoy and diplomatically dubbed him the best on the opening day of the Venice Film Festival.
McAvoy, 28, reciprocated the compliment saying, "I was blown away by Keira. The amount of poise and grace she has is just incredible."
, a war drama set in 1935, Knightley plays plays Cecilia Tallis, an upper-class beauty whose fledgling love affair with the housekeeper's son (James McAvoy) is destroyed by a tragic misunderstanding.
McAvoy – who is married to British actress Anne-Marie Duff – told PEOPLE he was enjoying Venice "very much," adding, with a smile, "it's very romantic."