It may not have been how the Celtics envisioned it at the start of the season, but as the playoffs approach, they’re driving forward with their championship ambitions — regardless of the starting point.

On Tuesday, the Celtics locked up the fourth spot in the Eastern Conference with a 101-93 loss to the Bulls in Chicago (click here for the full recap). They will face either the Bucks or Heat in the first round of the playoffs. The Heat can secure the fifth seed with a win over the Nets on Wednesday.

“It is what it is,” Boston coach Doc Rivers told reporters following the loss. “You know, I would like the three, two, or one, but we didn’t get it. It’s going to be a tough series, whoever we play, but we’ve just got to be ready to play.”

Even though Rivers had eyed rest of some of his starters on Tuesday (Kevin Garnett in particular), no one was taking the Bulls lightly. They couldn’t afford to — their opponents were looking to steal the eighth seed from the ailing Raptors. Derrick Rose (career-high 39 points) and Kirk Hinrich (30 points) made sure the Bulls got the job done.

“You knew if it came down to desperation, we’re in trouble,” said Rivers. “When you have one team fighting for their lives and the other team that can play in the third or the fourth seed, you knew no matter what that would be tough. And I was really concerned that if it was close down the stretch, you knew that that would be a difficult game.”

Here are three things we learned as the C’s look forward to the postseason:

PAUL PIERCE HAS HIS GROOVE BACK

While clinching the fourth seed was not cause for celebration, Rivers did find something to smile about in the loss.

“The silver lining for me was Paul (Pierce),” he said. “That’s two games in a row now that he was basically unguardable. That’s, going into the playoffs, that’s the best timing that we could possibly have.”

Pierce scored a team-high 28 points against the Bulls. Just three days earlier, he led the Celtics with 24 points over the Bucks. He is shooting 65 percent (22-for-34 from the field) in the last two games alone.

Rivers could not be happier to have his captain, who missed ten games with knee, foot, and thumb injuries, playing this well at the end of the regular season.

“I’m feeling good, man,“ Pierce told reporters. “My body is pretty much healed. This is exactly where I want to be at this point in the season. So I feel like I’m getting into a nice groove offensively, and I think that’s something we’re going to need going into the playoffs. Hopefully I can just keep it going and do the things necessary for to help this team win.”

In addition to Pierce, Rivers was also pleased by the performance of Kevin Garnett (14 points, nine rebounds), saying, “You know who actually looked great tonight too was Kevin. He had his legs back.”

PUTTING DEFENSE FIRST

The Celtics first round opponent may be undecided, but once that team is determined, don’t expect it to change their top priority — defense.

As proven on Tuesday, a player like Pierce or Ray Allen (25 points) could be on-point, but their contributions won’t make a difference if they aren’t shutting their opponent down on the other end.

Boston entered Tuesday’s game holding opponents to an average 95.4 points. While this falls in line with both potential first-round matchup Miami (averaging 96.5 points per game) and Milwaukee’s (97.7 points per game) scoring averages, the Celtics gave up over 100 points to the Heat on two occasions this season.

Pierce stressed the importance of gritty D in the playoffs.

“The key for us is going to have to be our defense,” he said. “I told the guys we didn’t get one stop the last three minutes of the game. It doesn’t matter what I do offensively — I can help carry the team offensively but if we don’t get these stops, it’s going to be tough for us to win.”

A LOOK BACK AT THE ROAD TRAVELED

With a loss to the Bulls, the Celtics wrapped up the regular season 26-15 on the road. It is one win off of last season’s record (27-14) and five wins shy of the 2008 mark (31-10).

The biggest comparison, though, is that with this season’s home record. The C’s are 24-16 at the Garden with one game left to play. Even if they defeat the Bucks on Wednesday, they will fall far short of their 35-6 records established in both 2008 and 2009.

There were high points on the road this season (such as sweeping the Texas Triangle) and low points as well (the image of Baron Davis’ buzzer-beater is still vivid). Here is a look back at the ups and downs away from Boston:

Most Memorable Win: Oct. 27, 2009 at Cleveland

Starting the season on the road against the Cavaliers was no easy task. It had been five years since the Celtics won in Cleveland, and the Cavs lost just two games at home the previous season. LeBron James and Co. looked poised to rule their turf, but the Celtics had other plans.

Playing with Kevin Garnett for the first time since March of 2009, the Celtics defeated the Cavaliers, 95-89, to kick off the regular season. The C’s overcame a first quarter deficit by shooting 5-for-6 from 3-point range in the second quarter alone (9-for-19 on the night). In spite of James scoring 38 points, Paul Pierce posted 23 points and 11 rebounds while Garnett also recorded a double-double with 13 points and 10 rebounds. Rajon Rondo dished 10 assists.

Even though the Celtics did not put too much stock into a single game, they proved the Cavs could be defeated at tone and started the season on a promising note.

Loss Best Forgotten: Jan. 28, 2010 at Orlando

A lot changed in between the Celtics trips to Orlando. After beating the Magic on Christmas Day, the C’s dropped five of their next eight road games, starting with a buzzer-beating loss to the Clippers.

They had every opportunity to snap the skid. Instead, they let the Magic take it right out of their hands. The Celtics blew a 16-point advantage and were outscored 35-22 in the fourth quarter alone. Orlando didn’t take its first lead until 4:52 left in the game, but they had built enough momentum at that point to carry them to the very last play. Rashard Lewis connected on the game-winning layup with 1.3 seconds to go, and the game ended 96-94.

The stumble exposed the Celtics inconsistencies over 48 minutes and sparked a three-game losing streak in which they fell to the Hawks and Lakers (they were also outscored in the fourth quarter in those losses).