What constitutes a rivalry? Decades of history between two teams? Geographical border battles? Magic-Bird-like matchups? Championship banners? The villainous against the virtuous?

Or can it just be a gloves-off coupling between two really good teams that have shown they don't like each other much?

Tyrese Haliburton was asked this question on New Years Day, after his Indiana Pacers defeated the Milwaukee Bucks at Fiserv Forum. Have the Bucks and the Pacers begun – on some small scale – a rivalry of their own?

Haliburton, Indiana’s gifted point guard, who hails from Oshkosh, wasn’t sure. He only knows the Bucks are a division rival and they stand in his way. That's it.

But one thing is for certain. The Bucks-Pacers playoff race practically guarantee a fierce clash.

Here’s a contextual look back at some of the dustups, some very real, some greatly over-exaggerated, from the five regular-season games between the Bucks and Pacers this season, which Indiana won four, for just a few examples why this playoff matchup could be dramatic and lengthy:

Giannis and the game ball

In Milwaukee's one win, Giannis Antetokounmpo scored a career-high and franchise-record 64 points against the Pacers on Dec. 13. But the secondary story-line was this: The Indiana Pacers took the game ball and gave it to their own Oscar Tshiebwe, who scored his first career regular-season point. In search of the ball, Antetokounmpo could be seen confronting the Pacers before bolting toward Indiana's locker room with teammates following.

The Bucks looked ticked off.

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

Not prepared physically?

The Bucks and Pacers played each other with a heightened level of intensity all year. But how about in physicality?

In that same story, ESPN quoted Milwaukee forward Bobby Portis saying this in reference to Milwaukee's win:

"We kind of bullied them that game. 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."

Haliburton took note of those comments later on.

"I think their words were, 'We were not prepared for them physically.' So we had to respond the right way," he said on Jan. 1 in Milwaukee, when Indiana responded with a 122-113 win at Fiserv on Jan. 1.

More: Is Bucks-Pacers a rivalry? Oshkosh native Tyrese Haliburton says not yet

Stealing 'Dame Time?'

Ok let's go back a bit to where it started. Remember that brand new in-season tournament in Las Vegas back in December? The Bucks and Pacers clashed then in the semifinals. This is what our beat reporter Jim Owczarski reported:

Haliburton knocked down a clinching three-pointer and the Pacers won 128-119, their second victory over the Bucks in a month. Haliburton looked down at his wrist – a nod to Milwaukee guard Damian Lillard and his famous “Dame Time” end-of-game gesture.

Afterward, Lillard commented on Haliburton’s celebration.

“I learned as a kid, when you dish it out, you've got to be willing to take it,” said Lillard. “For as many times as I've done it to people, I can't be upset when somebody else does it, you know what I mean. I think that's also a sign of respect and acknowledgment for knowing my history and knowing what I do. I didn't mind it. It was what it was.

“I've also known that, when you are having your moment, it's important to be careful, to be humble in your moments because you just never know how the tables are going to turn or when they are going to turn. I respected it. We shook hands after the game. I wasn't moved by it left or right.”

Oh – about those post-game hand shakes

Then came a Bucks-Pacers game later in December. When then-Bucks coach Adrian Griffin gave Antetokounmpo the green light to break Michael Redd’s franchise record of 57 points, the Pacers took that as a sign of also running up the score (to 140 points).

"No point commenting on it," the Pacers coach Rick Carlisle said. "I think it's pretty obvious what the answer is."

Here's further reporting from Owczarski:

In the moments following the conclusion of the game, Bucks assistant coach Josh Oppenheimer had an animated conversation with Pacers assistant coaches Mike Weinar – who happened to have a game ball in his right arm – and Lloyd Pierce. Haliburton was there also, and Bucks forward Thanasis Antetokounmpo ran over to him to shake hands. Haliburton briefly acknowledged it, and Antetokounmpo tossed up his hands and ran off.

The conversation between coaches and Haliburton continued, at which point Giannis Antetokounmpo left the postgame prayer circle at halfcourt to see what was happening. Khris Middleton and Jae Crowder also went over. Middleton, who rarely expresses emotion, was heated in his conversation with the Pacers. The Bucks were not impressed at the lack of sportsmanship, apparently.

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

Malik Beasley: 'It's not gonna be pretty'

A few days after the Jan. 1 game, Bucks guard Malik Beasley did an interview with Chris Haynes of Bleacher Report - where he predicted this very playoff matchup. And then, he slid in kind of a promise of payback. Here's what he said:

✂️ Video: Malik Bealey on Pacers

"I think it comes down to, for us, how they got our number, there's certain teams that just (have) your number. We're still trying to figure that out because I know we're gonna play them in the playoffs and, boy, it's not gonna be pretty. It's not gonna be pretty for them," Beasley said.

Reminded of those comments more than three months later after practice in Milwaukee this week, Beasley, to his credit, didn't say anything wild or weird. And his response hardly sounded like motivational inspiration for the Pacers, or arrogance; it really just sounded like Beasley believing in his own team. But these things are subjective; so you judge:

"I said it's not going to be pretty for them; I still stand by that. Kudos to them, if things are different - but I don't see that happening. I see us coming out with energy, coming out with defense and stopping the other team."

The Haliburton factor

Earlier this week, Milwaukee reserve Thanasis Antetokounmpo asked fans to make Fiserv Forum a tough place for the Pacers to visit.

But there will be those rooting for Haliburton, who finished the season leading the NBA with 10.9 assists per game; the Pacers, as a whole, also stood out with 30.8 per game.

You will certainly hear his cheering squad at Fiserv Forum, too. More than 100 people were wearing his jersey and Pacers gear and waited for him after the regular season game in Milwaukee to greet him personally; there were so many Haliburton fans the Fiserv Forum ushers had to issue a countdown for them to finish up and leave the arena to close up shop for the night.

Don't grab the popcorn

You'll miss something.

Here's the truth about the NBA. It's a pretty close-knit league. Away from the game, the players do tend to show each other a great deal of respect. There's a lot of friendships. There's a lot of mutual understanding about the grind, the pressure, the demands. Their on-court stuff is often in the spirit of intense competition.

But boy when these two teams met this year, there was a lot of trash chatter on the court and this season, it was easy to hear and see if you're focused on it.

When the Pacers beat the Bucks again, on Jan. 3, 142-130, Haliburton was actually looking toward Brook Lopez and Middleton and saying "Oh wow, one game, one game" – while he was in the act of free throw shooting. Perhaps in reference to Milwaukee's one win against Indiana this season.

Lopez was also pretty animated over a foul called and audibly complained (more than usual) to the refs.

Andre Jackson Jr. got in to it with Indiana's Isaiah Jackson...

And Haliburton could be seen right by the scorer's table as officials reviewed a call, that in fact, went for him and against Dame. Nothing contentious here, he was just so invested in the game.

For a Bucks team that has been through some crazy adversity this year that has at times left them looking flat, it would be shocking to see that in this series. Honestly, when Bobby Portis got ejected in one of the games after he saw the Pacers windmill tackle Giannis Antetokounmpo on a drive, it was one of the best demonstrations of his team loyalty - which he's known for - in his career. There's a clip of it:

Several of the Bucks have commented all week – like Middleton and Lillard – that they will be mindful of emotions not getting in the way of the game.

But they all know; action speaks louder than words. When it comes to these two teams, this year, will that be easier said than done?

This article originally appeared on Milwaukee Journal Sentinel: Nickel: Bucks and Pacers status? It's complicated