While Americans were busy eating way too much turkey, mashed potatoes and stuffing, the Duchess of Cambridge left baby George and Prince William at home to spend last evening at the annual SportsBall in London, in support of SportsAid. She has been patron of the organization SportsAid for about a year now, since falling in love with what the charity does during summer 2012's Olympic and Paralympic ceremonies. Remember that time Kate played volleyball in wedges? Yep, that was also for SportsAid!

Kate looked lovely in a black laser-cut Temperley London dress, the Templeton dress from the Autumn/Winter 2012 collection. She paired the cocktail dress with her black suede Jimmy Choo pumps and her diamond bracelet believed to have been a wedding gift from Prince Charles. She carried her bright red Alexander McQueen clutch as a pop of color -- a look we've seen before when the Duchess wore a black floor-length lace Temperley gown to St. Andrews, carrying the same red bag.

The most notable part of Kate's outfit to us, however? Her hair! Kate debuted a much darker hue, ditching her ombre locks she's been rocking over the past few months. She also clearly has had a cut, as her curls are quite a bit shorter. The hair coveted across the world had a very glossy night out!

Kate attended the Ball to support SportsAid, but also to present the One-to-Watch Award, announced after dinner. The award which honors an up-and-coming talent among young British athletes went to a young athlete named Amber Hill.

Click through the gallery above to see more photos from last night's event!