Jayson Tatum appears to be in good spirits after undergoing surgery on his Achilles, giving fans a thumbs up in his first social media post since Monday's devastating injury. 

Tatum underwent surgery Tuesday in New York after he suffered a ruptured Achilles late in Boston's Game 4 loss to the Knicks at Madison Square Garden on Monday night. Tatum suffered the non-contract injury when he pushed off his right foot as he lunged for a loose ball the Celtics had turned over. He crumbled to the floor in pain and remained down for several minutes.

Tatum was helped off the floor and couldn't put any weight on his leg, and was later seen covering his face as he was wheeled around Madison Square Garden.

While his right leg and foot were completely bandaged and (most importantly) elevated, Tatum looked much better from his hospital bed in his Wednesday afternoon post to Instagram. 

"Thank you for all the love and support," Tatum wrote, giving fans a thumbs up in the picture.

"The comeback will be greater than the setback," the Celtics wrote on a post on X sharing Tatum's photo.

Head coach Joe Mazzulla said during his pre-Game 5 chat with reporters that he's been talking with Tatum via text, and revealed Tatum sent a message to his teammates and the coaching staff on Wednesday.

"He's doing the best he can. If there's anyone that can handle it, it's him," said Mazzulla. "He sent a message to the staff and the players today, so he's doing better.

What that message was will remain a mystery though, as Mazzulla didn't want to share what Tatum said.

"I'm not telling you that," the coach replied tersely. 

As for Mazzulla's message to the team ahead of a must-win Game 5, he said he had to find a balance between the hurt of losing Tatum and focusing on the team's task at hand Wednesday night.

"You're empathetic for a brother of yours being in the position he's in. At the same time, we step into the arena tonight in a must-win situation. You have to find the balance of understanding the importance of him and how that hurt, and at the same time use some of that in the situation we're in and focus on the things that impact winning," he said. "It's a balance of both of those things; you can't have one without the other and you have to do both of those things."

Ahead of the game, the Celtics shared a photo of Torrey Craig sporting a No. 0 wristband during shootaround.

The release from the Celtics announcing Tatum's injury on Tuesday did not provide a timeline for his return, but did say "he is expected to make a full recovery." While that is certainly promising, it's going to take a while.

Tatum's father believes his son will return in 8-9 months, per Marc Spears on Wednesday's NBA Today on ESPN. But that sounds a bit advantageous. 

While Tatum is a 27-year-old superstar athlete in peak shape, coming back from an Achilles injury is a long and grueling process for anyone. Most players return one year following the injury, though it takes about another year for them to really return to form on the court -- if they ever return to form. Kevin Durant took 18 months off after he suffered a rupture Achilles in May of 2019, and didn't return until December of 2020. That timeline was aided a bit by the NBA season starting late due to the COVID bubble.  

But considering Tatum's age, his athleticism, and commitment to his craft, there's reason to feel optimistic he'll be back to making a lot of buckets and bringing an all-around game to the Celtics somewhere down the road.