The basketball world received some terrible news on Christmas Day with the passing of Boston Celtics legend KC Jones. The Celtics announced on Friday that the Hall of Fame point guard passed away at the age of 88. Fellow C's legend and former teammate Bill Russell was one of the first to come out with a public message mourning the death of his good buddy.

Russell took to Twitter to share his grief:

As made evident by his post, Russell and Jones were close friends, which makes it obvious why the former appears to have been direly affected by the passing of someone who's had a significant impact on not just the NBA and Celtics franchise, but as his friend.

Jones was a player for the Celtics between 1958 and 1967. During his nine years with Boston, he was able to amass no less than eight NBA championships. The 6-foot-1 point guard played alongside Russell, as they both played key roles in what was one of the most successful eras in Celtics franchise history.

After his playing days, Jones became a head coach in the NBA. Over a career that spanned more than two decades, Jones had coaching stints with several teams, including the San Diego Conquistadors, Washington Bullets, Milwaukee Bucks, and Seattle SuperSonics, among others. However, Jones is most known for being the head coach of the Celtics between 1983 and 1988, which resulted in two NBA titles and four Eastern Conference championships.

It is worth noting that Jones is currently the only other African American to have won multiple NBA titles, with the other being Russell himself.