Former world No. 1 Venus Williams welcomed an extra-special guest onto her Instagram Live shot, Wellness with Venus when 23-time major champion and little sister Serena joined in for a light workout and Q&A.

The Williams sisters, who were last in action at the Wimbledon Championships in June, were teaming up to raise awareness and money for Girls, Inc., a non-profit aiming to empower young girls to become leaders for the future.

Delighting fans with their effortless chemistry, Venus and Serena shared plenty of laughs through the 20-minute fitness session and reminisced on some of their favorite memories from their time on tour—including one anecdote about Venus hiding a sprained thumb from Serena during Wimbledon in 2008, where they faced off in the singles final and won together in women's doubles.

"Meanwhile, I lost that final!" Serena laughingly recalled.

Check out the full video right here.