Celtics legend and 11-time NBA champion Bill Russell tweeted out a photo Monday night ahead of "Monday Night Football" in what appears to have been a gesture of solidarity with current athletes and their reactions to comments from President Donald Trump disparaging those in the NFL who protest during the national anthem.

In the photo, Russell is shown on one knee with the Presidential Medal of Freedom around his neck and his eyes looking deep into the camera.

"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.

Russell, now 83, was inducted into the Basketball Hall of Fame in 1975 and is a five-time NBA MVP winner.

Russell was awarded the Presidential Medal of Freedom by President Barack Obama in 2011, where the 44th President pointed to Russell as a model of integrity for standing up for his beliefs through the years.

"Bill Russell the man is someone who has stood up for the rights and dignity of all men," Obama said of Russell at the ceremony. "He marched with King. He stood by Ali. When a restaurant refused to serve the black Celtics, he refused to play in the scheduled game. He endured insults and vandalism but he kept on focusing on making the teammates who he loved better players, and made possible the success of so many who would fall. I hope that one day in the streets of Boston that children will look up to a statue built not only of Bill Russell the player, but of Bill Russell the man."

Boston erected a statue in Russell's honor two years later, unveiling the bronze figure at a ceremony on Nov. 1, 2013.