STANFORD, CA, USA – World No.1 Serena Williams might not be in the draw at the Bank Of The West Classic, but she’s never too far away from the action. Eagle-eyed fans who turned up to top seed Venus Williams’ practice session got a treat as she was joined on court by her younger sister.

Venus started out the day the way she normally does at a new tournament: hitting the practice courts. The No.1 seed hit a few balls as she warmed up on center court ahead of her opening match tomorrow.

Good morning from @Venuseswilliams on main draw day here at @GoStanford! #BOTWClassic pic.twitter.com/G96YznB4Zg

— BOTW Classic (@BOTWClassic) July 18, 2016

But who was there on the sidelines, keeping a close eye on her older sister’s practice session and dance break?

One court, two Williams sisters. Coach #Serena? #BOTWClassic pic.twitter.com/XUBk3vRrSW

— BOTW Classic (@BOTWClassic) July 18, 2016

World No. 7 @Venuseswilliams with the ultimate @BrunoMars dance break. #BOTWClassic pic.twitter.com/dRzIOFrHML

— BOTW Classic (@BOTWClassic) July 18, 2016

After a quick warmup of her own, Serena decided to join in on the action and hit the tennis court herself as the Williams sisters tuned up their doubles.

Together! @serenawilliams can't help join in on a little fun with @Venuseswilliams. #BOTWClassic pic.twitter.com/sSAE2ju4oB

— BOTW Classic (@BOTWClassic) July 18, 2016

Practice is always better with your best friend. Olympic preview? @serenawilliams @Venuseswilliams #BOTWClassic pic.twitter.com/KRhnaseheh

— BOTW Classic (@BOTWClassic) July 18, 2016

You can watch every minute of Venus and Serena’s impromptu training session in Stanford right here. Check out the full live stream courtesy of Stanford and Tennis On Facebook: