Ailing Celtics Marcus Smart and Tyler Zeller are hospitalized

Celtics center Tyler Zeller is dealing with a sinus infection.matthew j. lee/globe staff/file 2016

The new year got off to a bit of a rocky start for the Celtics, as two players were hospitalized and another suffered an injury.

Guard Marcus Smart (gastrointestinal) and center Tyler Zeller (sinus infection) were hospitalized Sunday and remained there as of Monday afternoon, as the Celtics returned to practice after a two-day break.

Also, guard James Young sprained an ankle during an individual workout Sunday and missed practice Monday.

A stomach bug has been circulating within the team, affecting players, coaches, and staffers. Guard Avery Bradley missed Friday’s game against the Heat because of it, but returned to practice Monday. Assistant coach Jay Larranaga missed the last two games, too.

“It’s one of those things when you hang out together all the time,” said coach Brad Stevens.

Stevens said Zeller has dealt with an ear infection and sinusitis for a couple of weeks, but that the condition worsened Sunday. The coach was hopeful that Smart and Zeller would be discharged and able to rejoin the team soon. The Celtics recalled Demetrius Jackson and Jordan Mickey from the Maine Red Claws as temporary reinforcements.

Bradley went to TD Garden Friday afternoon but was sent home by the team’s medical staff prior to the win over the Heat. He took part in all of Monday’s practice.

“I’m feeling better,” he said. “I’m still a little under the weather. It felt good to get a practice today and go as hard as I can to try to get it behind me.”

Point guard Isaiah Thomas, for one, is hopeful that the Celtics will be whole and healthy again soon. He said he is not worried about being the next one to catch the bug, either.

“I only fist-bump anyway,” he said. “I don’t shake nobody’s hand. When I go through doors, I go through doors [putting my shirt over my hand]. And I don’t get sick.

“So I’m good. I don’t know the last time I got sick.”

Thomas is outdone

Thomas said he received a flood of text messages from current and former NBA players and his former coaches following his historic 52-point performance against the Heat. Thomas scored 29 points in the fourth period, setting a franchise mark for a period and falling just 2 points shy of Wilt Chamberlain’s NBA record for fourth-quarter points, which he set in his iconic 100-point game.

“It always feels good, especially to have your peers take notice,” Thomas said. “It’s people who always supported you. They’ve always been like that. The people who reached out, it’s been kind of the same people throughout my whole career. So it was a cool night.”

Thomas’s dominant game was the story of the NBA on Friday, but that did not last long. On Saturday, Rockets guard James Harden registered 53 points, 17 assists, and 16 rebounds in a win over the Knicks.

“He didn’t even let me get 24 hours,” said Thomas, smiling. “He had to kill my little shine. But that was unbelievable what he did. That’s probably never going to happen again, other than by himself. That was an unbelievable game. I was watching a little bit of it, too.”

Bowled over

On Saturday, Thomas traveled to Atlanta to watch his alma mater, Washington, face Alabama in the college football playoff semifinals. The fourth-seeded Huskies lost to the top-seeded Crimson Tide, 24-7. Thomas was disappointed by the result, and in disbelief about the opponent.

“It was nice, other than Alabama,” he said. “They’re not a college team. Those kids, like, they’re younger than me. They’re not in college. They can’t be. Like, those guys are huge.

“But it was a good experience. That was my first bowl game, and just to get back in that college atmosphere was fun. It was nice.”

Thomas said plenty of Huskies fans noticed him and congratulated him on his 52-point performance, too.

“It was good to be around those type of people again, and I was happy I went,” he said. “It sucked we lost, but at least we lost to an NFL team.”