McEnroe spoke on Williams’ retirement plans during a promotional interview for his show.
He compared her to great athletes like Muhammad Ali, Michael Jordan, and Tom Brady.
His show of support comes nearly five years after he made sexist comments about her.
Eva Longoria previously showed her love for Williams during a red carpet event.
She said she could relate with the tennis star's sad decision to focus on her family.
The actress added that women constantly had to find ways to balance being moms and career seekers.
Michelle Obama cheered Williams on with a sweet Instagram post.
She reflected on her years as a queen who dominated her field.
Fans loved seeing the tribute from the former FLOTUS and they stated it in the comments.