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The Boston Celtics earned their first NBA championship since 2008 and their 18th overall after a 106-88 win over the Dallas Mavericks in Game 5. Per usual, the basketball world had some worthwhile reactions on social media.

"What can they say now," said Paul Pierce, who was the Finals MVP during the Celtics' 2008 title run.  

Monday's result helped the Celtics pass the Los Angeles Lakers for most NBA titles. Magic Johnson -- who helped win five of the Lakers' 17 trophies - shared a post about the record shift, where he expressed his disappointment that Boston has eclipsed Los Angeles. 

"I hate that the Celtics officially have more championships than us now," Magic wrote. 

Former NFL quarterback Tom Brady won six of his seven Super Bowl rings with the New England Patriots, and he is still showing love to the city of Boston:

This was Kyrie Irving's first full-length season playing alongside Luka Doncic and the Mavericks, and he had an uplifting message for his team after the loss.

"Tribe, stay together no matter what," Irving, who played for the Celtics from 2017-2019, wrote. "Through the ups and downs, wins and losses, success and failure. Keep your head up high. This mission is bigger than us. I love you all!"

Dirk Nowitzki, who won a championship with the Mavericks in 2011, also chimed in.

"Great run @dallasmavs Heads up!! We will be back!!!," wrote the 14-time NBA All-Star.

After falling behind 0-3 in the series, the Mavericks had punched back with a 124-84 win in Game 4. However, the Celtics were clearly the more dominant team, and Monday's clincher was an uneven contest. This created mixed reactions in the social media world. 

"Snooze-fest of a finals," Andrew Bogut, who won the 2015 title with the Golden State Warriors, wrote on social media before the game was over. "Boston too good, or Dallas bad? Mix of both?"

"Mogs talkin bout this was boring…speak for yaself Boston just put on a show in a closer," said Iman Shumpert, who earned a ring with the Cleveland Cavaliers in 2016. "Luka and Ky didn't shoot it well for the highlights but how efficient has Jrue been?"

The Milwaukee Bucks' Patrick Beverly was also watching the Celtics get the job done.

"Impressive," Beverly wrote. 

Memphis Grizzlies star Ja Morant celebrated the win for Xavier Tillman, his former teammate. 

The NBA world was on its feet from the get go, when Boston's Payton Pritchard hit a halfcourt shot at the halftime buzzer. He had already hit a similar halfcourt shot during Game 2, but it still left many basketball stars in awe.

"He really don't be missing these," Morant said.

The Atlanta Hawks' Trae Young was also impressed and said he didn't doubt the ball was going in. 

"I called that Payton Pritchard shot,' Young wrote. "He really be making those!"

In all, it was another fun night for the "NBA Twitter" world. And now, we'll have to wait until free agency for the next round of player reactions. 

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