 -- A tweeted photo of Bill Russell kneeling while wearing his Presidential Medal of Freedom surfaced Monday in an apparent gesture of solidarity to the sports world's reaction to President Donald Trump's recent comments regarding protesting NFL players.

A solemn-faced Russell, bearing his trademark white goatee and crew cut, is shown bent to the floor in what appears to be the beige-carpeted room of a home, balanced on his right arm with his other arm resting on his thigh, looking intently into the camera in a light-blue T-shirt and khaki slacks.

"Proud to take a knee, and to stand tall against social injustice," the photo's caption reads, followed by the hashtags #takeaknee #medaloffreedom #NFL #BillRussell #MSNBC.

Dangling from his neck is the?Presidential Medal of Freedom he was awarded by President Barack Obama in 2011.?The medal is the nation's highest civilian honor.

The photo appeared on an unverified Twitter account, created earlier this month, that had no avatar and just one tweet.

Russell, 83, inducted into the Hall of Fame in 1975, was an 11-time NBA champion with the Boston Celtics?and won five NBA MVP awards.?

The first player to win an NBA championship, college title and Olympic gold medal, he went on to become the first African-American to coach a team in one of the major professional sports.

Scores of players, coaches and executives across the NFL showed similar gestures in games Sunday and Monday in response to Trump's controversial comments regarding players who kneel during the national anthem.

Many players and coaches in the NBA also spoke out in support of the NFL movement on Monday as training camps opened across the league.

Information from The Associated Press was used in this report.