The top of the NBA's Eastern Conference couldn't be much more compact.

Entering Tuesday's action, four teams -- the Miami Heat, Milwaukee Bucks, Boston Celtics and Philadelphia 76ers -- were within a single loss of one another.

And, in serendipitous timing, all four were set to face off, with the Bucks playing in Philadelphia on Tuesday, followed by the Heat and Celtics squaring off in Boston on Wednesday -- a 24-hour span that could have delivered a pair of Eastern Conference semifinal previews.

Let's look at one key question surrounding each of the conference's top four teams as they prepare for the playoffs, and how each storyline played out in two high-level matchups.

The results -- a pair of close, competitive games with Milwaukee and Miami both winning on the road -- only whet the appetite for what should be a scintillating spring full of playoff action in the East.

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Is Lowry Miami's playoff X factor?

When Heat coach Erik Spoelstra was asked whether Kyle Lowry's do-it-all performance in Miami's win against the Celtics on Wednesday night was indicative of the kind of performances the Heat expected when they signed him last summer, Spoelstra smiled.

"Look, we've been on the other side of it," Spoelstra said. "There were many years that I just really did not like Kyle Lowry, because he was such a thorn in our side."

Spoelstra pointed to the seven-game series between the Toronto Raptors and Miami in the first round of the 2016 playoffs, which Lowry's Raptors won.

"As that series got deeper, the better he played in clutch moments," Spoelstra said. "You can't define it by an analytic or a number or a playcall ... he just knows how to make winning plays."

Lowry made all sorts of them Wednesday. He finished with 23 points (6-for-12 from 3-point range) and eight assists in 36 minutes. He played his usual brand of in-your-face defense despite collecting four fouls down the stretch.

"That's just a great luxury to have a Hall of Fame point guard who can choreograph your offense but also take on big challenges defensively on the other end," Spoelstra said.

It's been an up-and-down season during Lowry's first in Miami after nine seasons with the Raptors, particularly because he has missed chunks of time to deal with personal matters. After a rocky week that saw Miami relinquish three fourth-quarter leads and get pummeled at home by the Brooklyn Nets, this performance was vintage Lowry.

Coming into Boston, which had been the hottest team in the league over the past two-plus months, and winning a back-and-forth game was a perfect elixir to wash away the ugly moments of last week.

In last year's lopsided first-round sweep to Milwaukee, the Heat were exposed as a team that needed another playmaker. Adding Lowry gave them a guard who could helm their offense, remain part of the Heat's defensive identity and provide the kind of offensive jolt he gave Miami on Wednesday inside TD Garden.

"I think having a real live point guard that's a pass-first guy who has of late, 'Screw pass-first, I'm going to score first.' ... That's good," Jimmy Butler said. "I miss Goran [Dragic] like hell, I like handling the ball, Tyler [Herro] likes handling the ball.

"But having a guy like Kyle that's telling everybody where to go, knowing how to get everyone the ball. ... Yes, we needed Kyle Lowry."

How will Boston adjust to life without its anchor?

In Boston's first test without Robert Williams III, who will be sidelined at least four weeks after meniscus surgery, the results were a mixed bag.

Heat center Bam Adebayo controlled the game. In a reminder of what Adebayo did to Boston in the 2020 East finals, he finished with 17 points, 12 rebounds and eight assists. It wasn't a coincidence that he was a plus-12 in 33 minutes, and Al Horford, who struggled to 6 points on 2-for-6 shooting, was minus-14 in 34 minutes. Grant Williams, meanwhile, was 2-for-7 from the field, and missed all three of his 3-point shots in his first start in place of Robert Williams alongside the rest of Boston's usual starting lineup of Jayson Tatum, Jaylen Brown, Marcus Smart and Horford.

Meanwhile, Daniel Theis finished with 15 points on perfect 6-for-6 shooting in 17 minutes.

It's a reminder of the varying skill sets Boston must now use to match Robert Williams' impact at both ends of the court.

"We feel confident with the three bigs, [and] the versatility that they have," Celtics coach Ime Udoka said. "It's not the same as Rob from the shot-blocking perspective, but a lot of the similar things he was doing on- and off-ball, they're very capable of."

Robert Williams certainly could've helped in trying to contain Adebayo on Wednesday, even as a help defender. And, perhaps more glaringly, he could've given Boston a boost offensively with his ability to both create vertical spacing as a lob threat and create easy shots when it mattered most (Boston shot 6-for-22 in the fourth).

"It's definitely an adjustment not having Rob here," Horford said. "We have to find ways to be effective and we have to find other ways to score."

Even if fully healthy, the red-hot Celtics were bound to lose a game or two. Their 24-4 stretch through Sunday's win over Minnesota -- the game in which Williams injured his knee -- wasn't likely to carry forward at that clip. Still, Wednesday's game displayed the difficulties this team will face navigating the East playoffs with its defensive anchor off the court.

Splash Mountain is back: Could Lopez unlock the best version of the Bucks?

The Bucks have spent virtually the entire season with Brook Lopez, their starting center, watching in street clothes. He has played in only eight games -- seven coming in the past three weeks -- after undergoing back surgery on Dec. 2.

Tuesday night was an important test. How would Lopez, matching up against arguably the league's biggest and toughest to guard center, Philadelphia's MVP candidate, Joel Embiid, hold up over the course of the game?

The answer, it turned out, was quite well.

Lopez played 29 minutes and scored 17 points for Milwaukee -- 11 of which came all in a row to open the second half for the Bucks. More importantly, Lopez went 4-for-9 from 3-point range, helping create some of the space on the court for Giannis Antetokounmpo -- he finished with 40 points, 14 rebounds, six assists, a steal and three blocks, including the one that won the Bucks the game -- to operate.

That Milwaukee is 14th in the league in defense this season with Lopez, one of the league's best (and biggest) interior defenders mostly watching as a spectator, is not a shock. The part of Lopez's game that is forgotten, however, is how he can break the court wide open for Antetokounmpo & Co.

It's rare for a guy of Lopez's size (7 feet, 282 pounds) to be able to shape the game at both ends. And while he's not Milwaukee's most important player -- or even their third -- the Bucks looked like a team ready for the playoffs Tuesday with him on the court.

And for a team that has spent much of the season playing a combination of Antetokounmpo and Bobby Portis at center, getting another 30 minutes of high-level, big-man play made everything else fall back into the places they were so effective for the Bucks during last year's championship run.

On a night when there were plenty of reasons to smile for the Bucks, Lopez's return and his effectiveness might have been the biggest of all.

Will MVP-level Harden make more appearances for Philly?

After Tuesday night's loss, 76ers coach Doc Rivers said he and James Harden had spoken at length that morning about needing the guard to get back to being the scorer he was with the Houston Rockets, rather than operating as the distributor he was with the Brooklyn Nets.

And, after playing arguably his best game as a 76er -- 32 points, five rebounds and nine assists in 37 minutes in the loss to Milwaukee -- Harden said he felt it was a step in the right direction.

"I'm trying to get it right," Harden said. "I'm trying to be the best James Harden I can be. And I'm trying to make sure that I'm doing the things necessary to help my team win.

"[Rivers] just told me, to sum it all up, to just go out there be you. And that was kind of my mindset today, and it felt good to have that confidence from Doc."

The 76ers need the best James Harden he can be -- because that's the version they hoped they were acquiring from the Nets at the trade deadline. And, while Harden has had moments of brilliance -- he's averaging 23.0 points, 9.8 assists and 7.4 rebounds in 15 games as a Sixer -- he has failed to consistently play to the type of MVP level Philadelphia hoped for.

For example: Of the 133 players who have attempted at least 200 layups or dunks this season, only three are shooting under 50% from the field: the Orlando Magic's Cole Anthony, the Utah Jazz's Nickeil Alexander-Walker and Harden.

But Tuesday night was a vintage performance for Harden. He went 5-for-7 from inside the arc, had the step-back working (he went 4-for-10 from 3) and got to the free throw line 12 times. More importantly, he made short work of Milwaukee's experiment of having Wesley Matthews start the game guarding him. In the closing minutes, it was defensive stopper Jrue Holiday -- not Matthews -- checking Harden.

If Philadelphia can get that version of Harden on a nightly basis over the next few months, he will form the partnership with Embiid that the 76ers need to make a deep playoff run.