FOR GIANNIS ANTETOKOUNMPO, it was supposed to be a moment of triumph. He'd thrown down a thunderous dunk with less than 30 seconds left to give his team a 16-point lead, capping the Milwaukee Bucks' Dec. 13 victory over the visiting Indiana Pacers. Antetokounmpo's final dunk gave him a career-high 64 points, the most any Bucks player has ever scored in a game.

All he wanted was his prize.

As the final seconds ticked off the clock and the players and team staffers flooded the court, a frenzied effort began to secure the game ball -- on both sides.

Antetokounmpo wanted it to commemorate his record-setting night. The Pacers wanted it to give to rookie Oscar Tshiebwe, who scored his first career regular-season point that night.

Unsure of the ball's whereabouts, Antetokounmpo exchanged heated words with Pacers players and staffers before sprinting toward the Indiana locker room in search of the ball.

"People didn't see the way Indiana acted that night," a Bucks team source told ESPN. "You come into our house and take our stuff. Screaming, 'F-you. F-you.' Yeah, how's a guy going to react?"

Antetokounmpo questioned after the game whether he was in possession of the actual game ball, but camera footage showed a Bucks staffer collecting the ball almost immediately after the buzzer sounded. The ball Indiana received and gave to Tshiebwe was apparently an alternate.

"It was unnecessary, it was blown out of proportion," Pacers center Myles Turner told ESPN last week. "They had the ball the whole time. I think that was obvious. So I'll just leave it at that."

Yet something else had irked Antetokounmpo before he furiously began to ensure Milwaukee had possession of the ball. The two-time MVP was also upset that the Pacers had stormed off the court after the buzzer without shaking hands, team sources told ESPN, which Antetokounmpo saw as a sign of disrespect.

"Does everybody shake hands in the NBA after a game?" Pacers guard Tyrese Haliburton told ESPN while shaking his head.

"They tried to run up the score at the end," Turner told ESPN. "Giannis came in, came out, then we cut the lead to like 10 points in the garbage time -- they put all their starters back in and then they tried to run up the score. There's unwritten rules in basketball. We thought it was disrespectful and some guys reacted accordingly."

The heated exchange between the two teams, and its simmering aftermath, is exactly how rivalries are born. The two teams return to the scene of the fracas in Milwaukee on New Year's Day before heading to Indiana for a game on Wednesday, which will already mark their fifth meeting of the season.

Bucks-Pacers is one of seven regular-season matchups that will involve a fifth game this season, a byproduct of the in-season tournament and something no teams had done since the Heat and Nets during the 2003-04 season.

The Pacers beat the Bucks in their first two meetings this season, including in Las Vegas in the semifinals of the in-season tournament. So Milwaukee was determined not to allow Indiana to win a third straight in their most recent matchup.

"We kind of bullied them that game," said Bucks forward Bobby Portis, who was ejected in the fourth quarter of that Dec. 13 meeting. "I think they felt that presence. When a team beats you twice, you don't want to let them beat you three times because now they think they can play with you. We played with a sense of urgency. We were more physical, we were hitting them. I don't think they liked that."

FOR THE PACERS, the in-season tournament represented an opportunity.

After finishing in 11th place in the Eastern Conference last season, Indiana ran through group play undefeated, led by Haliburton, who made the All-Star team last year but is off to an even better start this season. The Pacers' dominance through the tournament earned the team the kind of national TV spotlight it hadn't experienced in years.

Meanwhile, Milwaukee has been a mainstay atop the East for years now, but the roster was upended a week before training camp when the Bucks acquired superstar Damian Lillard. But with two of the league's showcase stars working together, Milwaukee presented a formidable obstacle for Indiana, one small market team with aspirations of unseating another.

"They won a championship, man. Small market team that wins a championship, they obviously have a good formula," Turner said about stacking up to the Bucks. "They are in the division as well. I don't think we use other teams as measuring sticks, I don't think that's the best way to put it. We're running our own race right now. And seeing how we stack up against other teams and just growing from game to game."

Up until their loss in the championship game against the Los Angeles Lakers, the Pacers had used the tournament as a showcase for their top-ranked offense. Haliburton is averaging 24.6 points and leads the NBA with an average of 12.8 assists all while shooting 50% from the field and 41% from 3.

He has put up 20 points and 20 assists in back-to-back games entering Monday, joining John Stockton (1990) and Magic Johnson (1984) as the only players in NBA history with consecutive 20-point, 20-assist games, according to research by ESPN Stats & Information. No player has ever recorded 20 assists in three straight games.

"His offensive level is beyond elite," Indiana coach Rick Carlisle told reporters after Saturday's 140-126 win against the New York Knicks. "He's put a lot of work in the last two summers on reads, on being able to create rim pressure and to increase his range, and so teams are in a real bind."

And as Haliburton enjoys the moment, he's fueling the bubbling Midwestern rivalry, too.

During their in-season tournament semifinals matchup, it was Haliburton who sealed the Pacers' victory with a statement. With 48.0 seconds remaining, the Bucks were within five points when Haliburton nailed a step-back 3-pointer beyond the outstretched hand of Bucks center Brook Lopez, who finished second in the voting for Defensive Player of the Year a season ago. As Haliburton turned toward the crowd, he looked down toward his wrist in a nod to Dame Time, a move usually reserved for the iconic veteran guard.

Lillard says he harbors no hard feelings about the taunt, but acknowledged the games against the Pacers have been even more competitive because the two teams played with something on the line in Las Vegas.

"What was at stake the [second] time we played them is what made it into something," Lillard told ESPN. "And then what took place the third time, obviously made it even more. It makes for a little bit extra."

PLAYERS ON BOTH the Bucks and Pacers acknowledge the increased intensity in the games between the two teams so far this season -- and expect more of the same this week.

"There probably will be some extra juice to it for sure," Haliburton told ESPN. "How can there not be?"

But a rivalry? No one is willing to go quite that far just yet.

"We played in the in-season tournament," Haliburton said. "That's a real game, but we've got to have some more battles. We're 2-1 against them this year, but at the end of the day, they're a higher seed, we're a lower seed. For it to be a real rivalry, we've got to compete in a playoff game. It's got to happen over time."

Prior to this season, the Bucks had won 15 of their past 17 meetings with the Pacers, who haven't reached the postseason since the 2019-20 season, when they were swept by the Miami Heat in the first round. Had they won that series, they would've faced Milwaukee in the East semis.

A playoff meeting this season isn't out of the equation. The Bucks are currently second in the East; the Pacers are seventh. If those seeds hold, and the Pacers were to win their first play-in game, the two teams would face off in the postseason for the first time since 2000, when the Pacers beat the Bucks in the first round en route to their lone NBA Finals appearance.

It's a postseason matchup Antetokounmpo would surely relish. In three meetings this season, the two-time MVP is averaging 51.7 points on 72% shooting. But in assessing these next two matchups, Antetokounmpo remained dismissive.

"It's just another game, man," Antetokounmpo told ESPN. "Is it the playoffs? Why would I look forward to it?"