Isaiah Thomas knows how special it is for Boston to wrap up its season as a No. 1 seed, but he is concentrating on the Celtics' first-round matchup against the Bulls. (1:31)

BOSTON -- The Boston Celtics allowed themselves a brief moment to savor the accomplishment of earning the No. 1 seed in the Eastern Conference on Wednesday night, rallying around the notion that few considered that feat possible entering the 2016-17 campaign.

But unlike recent seasons when the team reveled in smaller goals -- sneaking into the playoffs two seasons ago or climbing the East playoff ladder a bit last year -- players were already seemingly focused on the next challenge by the time they departed the Celtics' locker room.

"We just want to win," Celtics All-Star point guard Isaiah Thomas said. "We're a totally different team than we were last year and the year before. We have some new pieces, we're playing at a higher level and we want more. In previous years we just kind of wanted to make the playoffs and see what happened. Now we want to advance, and advance as far as possible."

Added teammate Jae Crowder: "I think a lot of teams in the past were happy to be in the playoffs. We've got a much different feeling in the locker room. Playing on those teams, it's just a much different mentality. Everybody wants to actually win."

"We're a totally different team than we were last year and the year before," Isaiah Thomas said. Winslow Townson/USA TODAY Sports

The Celtics know some will be leery of their potential until they prove they can win in the playoffs. That's probably best for a team that has a chip on its shoulder and is fueled almost entirely by doubt.

Even before securing the top spot, the Celtics had heard all the chatter: that the Cleveland Cavaliers were the team to beat in the East regardless of seeding and that Boston hasn't proved anything by simply earning the top spot.

The Celtics don't exactly disagree with this. Coach Brad Stevens said before Wednesday's 112-94 win over the Bucks that the Cavs are the team to beat until someone dethrones them. And Thomas has said all season that he's eager to learn how to win in the postseason, peppering pal Tom Brady with text messages asking how Thomas can elevate his play on the big stage.

With Wednesday's finale finalizing the playoff path, the Celtics seemed almost relieved to simply arrive at the postseason. Finally, this team can embrace that next challenge and try to show it is not the same team that got swept by Cleveland in 2015 and bounced in six games by Atlanta last year.

Al Horford, a member of that Hawks team that defeated Boston, said he noticed something about these Celtics last season. He felt like he could help the team get to that next level, even as some of those around him suggested Boston might still be in building mode.

"I think that probably a lot of people around me didn't quite see it, but after playing [the Celtics] last year in the playoffs and just looking at the potential of our group, I just felt really strong about what we have here," Horford said. "I'm just happy to be a part of this."

Horford has repeatedly been asked this season about his decision to leave the comforts of the Hawks in order to explore the potential of the Celtics. Earning the top spot in the East in a small way validates his decision, and Horford spent Tuesday's practice gushing about how this is the most excited he has been for a playoffs during his NBA career.

But playoff success will truly determine if Horford made the correct decision.

The Celtics believe they have not played their best basketball yet. Part of the reason earning the No. 1 seed resonates with them is because they endured so many injuries and so many ups and downs over the course of the regular season that it's remarkable they ultimately topped the conference, finishing two games ahead of a Cavaliers team that prioritized rest at the finish line.

Boston wrapped up the regular season with not only the best record in the East but also, thanks to an ability to swap picks with the Nets, the best chance at landing the No. 1 pick in May's draft lottery.

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There's potential here for even more growth, regardless of how the postseason plays out. But maybe only slightly less important than the pingpong balls is Boston showing it's capable of winning in the playoffs. The deeper this team can penetrate in the postseason, the more intriguing it becomes to free agents this summer. With the right maneuvering, Boston can finagle max cap space to chase another big-name free agent.

One year after showcasing their potential in front of Horford, it won't be overlooked that the Celtics have drawn Jimmy Butler's team in the first round this season. While not a free-agent-to-be like Horford, Butler has drawn well-documented interest from Boston. It can't hurt for the Celtics to put their best foot forward in front of one of the league's top talents.

But these Celtics aren't overly concerned about the summer and beyond. They're focused on the right now.

"We for sure congratulated each other on a good season. Don't let that get twisted," Crowder said. "But we know we have a bigger picture ahead of us, so we just congratulated each other and told each other we know the season that's ahead. Good work this year, and we've got a lot more work to do."

The Celtics have put themselves in the best possible position for postseason success. The Bulls are a bit of a tough draw, given their playoff experience and how well they played late in the season. Still, Boston will be favored in the series.

Boston will benefit from having home-court advantage throughout the Eastern Conference playoffs, including a potential showdown with the Cavaliers, should both teams be fortunate enough to make it that far. Having the top seed would be most valuable then.

"It's a huge advantage," Horford said. "And I feel like we have the best home court, so we need to take advantage of this. This is a tough building to play in. And I know, for many years, I hated coming in here. I'm just excited to be on the good side."

For a Boston team that had to claw its way to simply snag the last playoff berth in the East two seasons ago, the No. 1 spot simply shows how far the team has come.

"They definitely weren't thinking No. 1 seed when I got here. I know that for a fact," Thomas said. "They were barely thinking playoffs. How fast it's come, it's good. It says a lot abut the direction this organization is going in and the work we put in as players and coaches."

Did Thomas think the Celtics had the potential to get to this point?

"I did," he said. "But I'm different from others."