Kendrick Perkins hilariously reacted to Paul Pierce's thoughts on him standing up to Shaquille O'Neal back in the day. Pierce and Perkins' Boston Celtics took on O'Neal's Cleveland Cavaliers in the second round of the 2010 NBA Playoffs. This was the year before LeBron James moved to Miami and O'Neal decided to call it quits. Their series against each other was tough, given how both teams kept trading blows. In the first four games, the series was tied 2-2, neither team showing weakness. However, Pierce recalled what motivated the Celtics to win their series against Cleveland.Paul Pierce shared that his former Boston teammate, Kendrick Perkins, once stood up to Shaquille O'Neal, a situation never seen before. Most NBA players feared Shaq because of his size and his dominance on the court. However, Perkins didn't back down to O'Neal's intimidating presence and even got into a heated argument with the big man. "(Kendrick Perkins) stood in Shaq's face like, 'I'd beat your a**,'" Pierce shared. "I ain't never seen nobody standup to Shaq. That gave me confidence like we're going to whoop them. ... If he doesn't get hurt, we win 2 rings."Perkins took notice of Pierce's remarks about him and gave a humorous response on social media:"I’m a changed man now 😂," Perkins wrote on X. Paul Pierce reveals why it hurt when his former Celtics teammate joined forces with LeBron JamesBack when Paul Pierce was part of the Boston Celtics' big three, including Kevin Garnett and Ray Allen, they had fierce battles with LeBron James, who played for the Cleveland Cavaliers at the time. If there was anyone who could stop Pierce and the Celtics from reaching the NBA Finals, it was LeBron.However, in 2012, Allen did the unthinkable and joined forces with James, who was with the Miami Heat at that time. It was a slap on the face to Pierce and Garnett, not because Allen left, but because their former teammate decided to team up with the player they despised playing against the Eastern Conference.“It was absolutely where he went,” Pierce told Shannon Sharpe on 'Club Shay Shay'. “You gotta understand, we’ve been battling LeBron for the last four or five years… The Heat aren’t our rival, it’s LeBron. He’s our rival. So like dude, we just played them in the playoffs a year ago, you can’t go play with them.”While this tarnished their brotherhood during that time, they ultimately hashed things out by 2017.