Sienna Miller says Keira Knightley will be 'amazing' mother

NEW YORK, Dec. 19 (UPI) -- Sienna Miller thinks Keira Knightley will be a great mother.

The 32-year-old actress said as much of the 29-year-old star to Page Six at the premiere of her new film, American Sniper. Knightley and husband James Righton married in May 2013, and revealed they are expecting their first child earlier this week.

"We've spoken a lot and I know she will be amazing," Miller told the publication. "She doesn't need any advice. She will be perfect."

Miller and boyfriend Tom Sturridge have been together since 2011, and welcomed their first child, Marlowe Ottoline, in July 2012. The actress spoke lovingly of her daughter in an interview for Vogue's January issue.

"I was overwhelmed by how normal it felt," she recalled. "It was like, 'There you are -- that's what I've been missing.' Like we're both in on something only we know. An amazing sense of being complicit with a little being."

Miller will next appear alongside Bradley Cooper in American Sniper, and is also scheduled for Mississippi Grind with Ryan Reynolds. Knightley last starred as Joan Clarke in The Imitation Game, and will portray Jan Hall in Everest in 2015.