The Celtics need more from Jayson Tatum, who scored just 10 points in Boston’s 103-101 loss to Milwaukee in Game 3 of the Eastern Conference semifinals on Saturday. Charles Krupa/Associated Press

MILWAUKEE — When Jayson Tatum outplayed Kevin Durant as the Celtics swept the Brooklyn Nets, Boston fans were more than happy to gas up their rising star. The MVP chants were plentiful at TD Garden, and even materialized at Brooklyn’s Barclays Center as Tatum evolved into a bonafide superstar.

Tatum has been in the conversation as a top-1o player in the league, but has taken it to a new level this season. He was knocking on the door as a top-5 player – and a rare talent who could one day compete for the MVP. Hence, the chants.

But Game 3 of the Eastern Conference semifinals against Milwaukee was the worst postseason showing of his young career. Tatum had just 10 points and three assists on 4-for-19 shooting in the Celtics’ 103-101 loss, which gave the Bucks a 2-1 series lead.

If Tatum wants to etch his name with some of the NBA’s greats, he can’t have games like Saturday. Not on this large of a stage. He knows as much.

“I’ve got to be better,” Tatum said postgame Saturday. “I know that. My teammates know that. And I’m sure I will be. And we’ll make some adjustments and just be a little bit better on Monday.”

It wasn’t just the missed shots Saturday; off-games happen to the best players. There were times where the Bucks loaded up on Tatum, allowing other Celtics to create better shots. Celtics Coach Ime Udoka said it’s a team effort getting Tatum open, which is fair considering the Bucks’ defensive personnel.

But that’s life as a top player. The Celtics loaded up against Durant, and they’re doing the same against Giannis Antetokounmpo. A similar young player in Luka Doncic – who’s also in that top-5 player conversation – is putting up numbers for the Mavericks despite a lean supporting cast.

To Tatum’s credit, he’s carried more of the offensive load the past few months. But that’s what made Saturday that much more jarring. Tatum’s case as a top-5 player comes from his two-way ability and overall impact on the game. The Celtics needed everything they could get, but Tatum couldn’t provide that production.

Of course, that’s a process: Tatum’s still only 24. He admitted he overthought the game Saturday, which led to him passing up shots the Celtics needed him to take. Game 3 could be a learning moment for Tatum on a smaller but similar scale to LeBron James’ 2011 NBA finals disappointment, which helped James round out his game to greatness.

“(Saturday) was just a one-off where I probably was thinking a little bit too much knowing that they give me a lot of attention,” Tatum said. “Obviously I passed up some open looks that would have been best for the team. It led to some turnovers and things like that. I just got to make better reads and a lot of times it was for myself today that I passed up.”

It’s not the first time this postseason Tatum has struggled finding his shots playing against a crowd. But that’s why his struggles Saturday were so jarring to watch. For example, when Tatum was 5-for-16 for 19 points in Game 2 against the Nets, he switched gears to add 10 assists. That version of Tatum would have been huge for the Celtics against the Bucks.

Tatum needs to bounce back in Game 4 on Monday. The Celtics will have a beast of a time if they fall behind 3-1 to the Bucks. Road victories don’t come easy in the playoffs, and Tatum needs to make up for his Game 3 performance.

“He knows how important he is to the team,” Udoka said. “We kind of go where he does to some extent. What he did after a lackluster Game 1, he bounced back in Game 2, and I look forward to him doing the same thing next game.”