The actress' feud started in May 2010 when Diaz began dating New York Yankees slugger Alex Rodriguez, who was previously linked to Hudson. At the time, an insider told Us Weekly Hudson felt Diaz only began dating Rodriguez as payback for hooking up with Justin Timberlake in January 2007 -- just two days after Diaz and Timberlake ended their four-year romance.
Knight and Day's Diaz split with Rodriguez in the fall; Something Borrowed's Hudson is currently engaged to Muse frontman Matt Bellamy, father of her 7-month-old son Bingham.
Diaz (in Victoria Beckham) and Hudson (in vintage Versace) weren't the only A-list beauties to hit up the Vanity Fair bash. The Avengers' Chris Evans shared a laugh with Sandra Bullock (in Marchesa), while David Beckham and Tom Cruise continued to flaunt their bromance. Other attendees included Natalie Portman, Jessica Chastain, Jennifer Lopez, Gerard Butler, Gwyneth Paltrow, Jane Fonda, Seth Rogen and Michelle Williams.
Earlier that evening at the 20th Annual Elton John AIDS Foundation Academy Awards viewing party in Beverly Hills, Katy Perry (in Blumarine) bid on a $100,000 cooking lesson from celebrity chef Cat Cora. She and movie producer Steve Tisch eventually split the once-in-a-lifetime experience after an animated bidding war. "Katy got up and hugged him delightedly," a partygoer tells Us. "She seemed a bit tipsy, but not messy at all."
John's bash also brought out a handful of A-list couples, including Anna Paquin and Stephen Moyer, Miley Cyrus and Liam Hemsworth and Nina Dobrev and Ian Somerhalder. Kim and Kourtney Kardashian also attended.