Kaley Cuoco gives first interview since Ryan Sweeting split, 'in great spirits' at tennis event

Kaley Cuoco was spotted supporting her longtime friends, tennis pros Bob and Mike Bryan, at the Bryan Brothers Tennis Festival on Sunday following her split from estranged husband Ryan Sweeting.

"Kaley came to the event yesterday and seemed in great spirits," an onlooker told ET. "She was very happy and friendly to everyone. The day was lighthearted and she was with her close friends having a good time. She was in a great mood."

WATCH: Kaley Cuoco Divorcing Ryan Sweeting After 21 Months of Marriage

She was also in a generous mood. The Big Bang Theory star donated four sets of four tickets to front row seats at the BBT Festival to be auctioned off and even took over emceeing duties from Bob and Mike's father, Wayne, to help auction them off.

"I love tennis and I love their foundation, so it means a lot to me," Cuoco told ET. "Bob and Mike have done so much for the sport of tennis in giving back in charities in Southern California and all over the world."

All proceeds from the event, which took place at Spanish Hills Country Club in Camarillo, California, went to the Bryan Bros. Foundation, which, according to the website, is "dedicated to helping support and develop the dreams of children in Ventura County and around the world."

"Bob and Mike have basically been my god brothers my entire life," Cuoco said. "Our families are very dear friends. Our parents are best friends. We go back a long time."

Cuoco grew up with twin brothers Bob and Mike in California, and it was the Bryans who set Cuoco up with her tennis-playing ex, Sweeting, in 2013.

WATCH: Kaley Cuoco Has a Girls Night Out After Divorce Announcement

"Had an amazing time today hangin at the #bryanbrostennisfest #bryanbrothersfoundation," Cuoco posted on Instagram, alongside a stitch of five photos from the event. "Loved seeing my friends @mikecbryan @bryanbros @lucillebryan and my favourite little Diaz girls!!! #mybestfriendskidsrock."

Despite the split, Cuoco has been having a good time around town. Just hours after the divorce announcement on Friday, the 29-year-old actress was photographed having a girls' night at The Village restaurant in Studio City, California. She and five friends, including her sister, Briana, were seen laughing and drinking wine while animatedly talking about Sweeting, according to an eyewitness.

WATCH: 12 Times Kaley Cuoco Gushed About Then-Husband Ryan Sweeting

Cuoco posted an Instagram photo of herself on Saturday without her wedding ring and introducing a new addition to the family -- a horse named Zaza.

Check out more of Kaley Cuoco in the gallery below!

More on ET Online.com:
Bindi Irwin's Boyfriend adorably cheers her on from 'Dancing With the Stars' audience
Matt Damon and Jimmy Kimmel hash out their decade-long rivalry in couples therapy
Matilda Ledger looks all grown up at Broadway show with mom Michelle Williams