Paul Pierce and Kevin Garnett were teammates in high school

Via Pierce's blog on Boston.com:

Kevin and I actually played together when we were in high school.

He played on my traveling team. I even got to bring him to my home in Inglewood! My AAU coach found Kev and talked him into coming and playing with us. Kevin had heard about me, but he hadn't seen me play at the time.

[...]

He came out and stayed with me and my moms. He was with me and he was talking about moving schools and I was trying to get him to come out to Inglewood that next year, because he was moving to South Carolina.

Then when we first established our relationship and it's funny, after that he just jumped ship.

I had no idea they played together before being on the Celtics. I'm really loving this Pierce blog.