From the day Mike Budenholzer arrived in Milwaukee last May, this has been a charmed run for the Bucks. They shored up the roster with a strong summer of free agency, debuted a stunning new arena, unlocked Giannis Antetokounmpo's MVP potential with a brand new offensive system based on spacing and shooting, then rampaged through the Eastern Conference to finish the regular season 60-22 and earn the No. 1 overall seed. Now, for the first time in nearly a year, they're facing something new: adversity.

Early on Sunday afternoon, the Celtics arrived in Milwaukee and delivered the kind of performance that was expected of them prior to the season, but that they had so often failed to deliver during a tumultuous campaign. Led by a healthy Kyrie Irving playing in his first postseason with the Celtics, and the ever steady Al Horford, the Celtics embarrassed the Bucks, winning 112-90 to steal home-court advantage and take a 1-0 lead.

As a blunt George Hill put it after the loss, "We felt like they came out and punched us in the mouth." The Bucks didn't have an answer on Sunday, but they'll have a chance to respond on Tuesday night in Game 2 (8 p.m. ET -- watch on fuboTV), and what they offer will tell us everything about this team. Are they a legitimate contender to the Warriors' throne? Or, as the doubters -- waning though they were as the season went along -- feared, are they a mere regular-season champ not fit for a sustained playoff run against other elite teams?

Jumping out to a 7-0 start, the Bucks proved early on that things were going to be different this season. They've been in at least second place in the Eastern standings since opening night, racked up an absurd 45 double-digit victories -- more wins than three East playoff teams had in total -- and lost consecutive games just once. Budenholzer's new schemes worked from pretty much Day One, and there was never any semblance of internal or external drama.

All of those are impressive accomplishments, and none of this is to say that teams should go through long losing streaks or start drama in the locker room on purpose; struggle for struggle's sake is not admirable. But it is to say that things have been easy for the Bucks this season. They haven't had to overcome any serious obstacles, because few ever materialized; they haven't had to deal with doubt or distrust, because there was never any reason for those problems to develop.

Now, in late April, in the second round of the playoffs, they're all of a sudden dealing with what Giannis called, "one of the toughest losses we've ever had all season." That's a tough time for a team to face their first serious bit of adversity. There is no margin for error anymore. The series is far from over, but that won't be the case if the Bucks don't come with the right response in Game 2. In NBA history, only 20 teams have ever won a seven-game playoff series after going down 2-0.

After Game 1 went even better than they could have imagined, there's no reason to expect any major adjustments from the Celtics. They're going to continue to form a wall at the top of the key in transition, and will always send multiple defenders at Giannis in the halfcourt to prevent him from getting to the rim. As the potential MVP, the simple fact is Giannis must play better than in Game 1, when he scored 22 points on 7-of-21 from the field, which was tied for the worst shooting performance of his career in games when he's taken at least 20 shots.

But it's one thing to know what's coming, and another to make the proper adjustment after playing a certain way all season. "They were loading a lot," Giannis said. "There were a lot of guys in the paint. When they were guarding the paint and I tried to spin or change direction, there was a second guy there. If they're going to play like this the whole series, i just have to make the right pass, and trust my teammates to knock down shots."

And what about those teammates? The Bucks, as great as they were all season, relied more on depth and volume of shooting than pure talent. Which means someone has to step up in the postseason, in particular if Giannis and Khris Middleton are struggling. That didn't happen in Game 1. Eric Bledsoe, Brook Lopez, Pat Connaughton, Ersan Ilyasova and George Hill went a combined 4-of-26 from downtown. More concerning, though, was that they started to pass up looks as the game went along. All season long, their motto has been, "Let it fly." Will they be willing to do that in Game 2 with the pressure mounting?

Those are the questions the Bucks are facing heading into Tuesday night's crucial second game, and the answers they provide just may define their season.