Luke Walton -- Wins Another Championship ... in Beach Volleyball!

It didn't take Luke Walton long to win his 2nd championship of the summer -- this time in beach volleyball ... and his teammates included Richard Jefferson and Matt Leinart.

The former NFL and NBA players were part of Team Fletch ... which won the coveted Six Man title in Manhattan Beach, CA this weekend. Two awesome things about the victory: First, the former pro athletes mostly rode the bench. Beach volleyball is serious biz in MB!

Secondly, Walton -- now an assistant coach with the NBA champ Golden State Warriors -- had to sport the rival Lakers gear, since that's also Team Fletch's uni.

Doesn't look like the Warriors minded the unintentional diss, since the team shouted out Walton's victory on social media.

Quick title count:
- Walton -- 3 NBA (2 as a player, 1 as asst. coach), 1 Six Man
- Leinart -- 2 1 NCAA, 1 Six Man
- Jefferson -- 1 Six Man