Prince Harry Attends Event With Prince William After Announcing His Brother as Best Man

Prince William and Prince Harry
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The brothers officially opened the Greenhouse Centre in London on Thursday.

Duty calls for Prince William and Prince Harry.

The 35-year-old Duke of Cambridge and the 33-year-old engaged royal attended the opening of the Greenhouse Sports Centre in London, England, on Thursday, just hours after it was announced that William would be Harry's best man on his wedding day.

The brothers received a tour of the facilities and met some of the young people taking part in the Greenhouse Centre, which will provide sport, coaching and social facilities for young people in the surrounding community. During the event, both Harry and William cut the ceremonial ribbon, officially marking the opening of the center.

Toby Melville - WPA Pool/Getty Images

Earlier that day, Kensington Palace shared the exciting news that Harry had asked his big bro to be his best man when he marries Meghan Markle on May 19.

“The Duke of Cambridge is honored to have been asked, and is very much looking forward to supporting his brother at St. George’s Chapel,” read the palace's statement. Harry served as William's best man in his and Kate Middleton's 2011 royal wedding at Westminster Abbey.

Meanwhile, William and the Duchess of Cambridge welcomed their third child, a baby boy, together earlier this week. The couple has yet to announce the newborn's name.

For more on William and Harry's engagements this week, watch the video below. And keep up with all of ET's coverage of the Royal Wedding as we count down to May 19!