2018 US Open Opening Night Gala, Kelly Clarkson, Gale King

USTA/Mike Lawrence

The 2018 U.S. Open has officially kicked off in Flushing Meadows!

The final Grand Slam of the year is only just getting started, but celebs are already flocking to the tennis event. Armie Hammer, Kelly Clarkson, Gayle King, Danielle Brooks, Vera Wang and Vogue's Anna Wintour are among the celebs that have already been spotted at U.S. Open festivities. On Monday, Hammer was spotted kicking off his birthday week in the Emirates Suite at Arthur Ashe Stadium.

The Call Me By Your Name actor, who is celebrating his 32nd birthday today, attended the U.S. Open with his wife, Elizabeth Chambers, and a group of their pals.

Hammer posted a group photo from their sweet spot at Arthur Ashe Stadium on Instagram with the caption, "The birthday shenanigans continue."

To see all of the celebs in attendance at the 2018 U.S. Open, check out the gallery above!

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