The Boston Celtics looked like they had the Atlanta Hawks down for the count in the first round, but the Hawks got off the mat in Game 3 and threw a big counterpunch.

So now the question becomes: how will the Celtics respond? Following the 130-122 loss in Game 3, which was one of Boston's worst defensive showings all year, the C's emphasized that the Hawks won't be an easy out.

With the series at 2-1 in Boston's favor, the Celtics will have an opportunity Sunday to steal a pivotal Game 4 on the road. But in order to do that, they'll have to correct the mistakes that plagued them in Game 3 (and even before that).

Here are three key adjustments Boston must make ahead of its Game 4 showdown with the Atlanta Hawks.

3. Lock in on offensive rebounding

Prior to the first round, many pundits and fans were looking at a potential Celtics-Heat first-round matchup. However, Atlanta had other plans in the Play-In Tournament, and the Hawks shocked Miami by dominating the offensive glass.

The Hawks have had a similar focus against the C's, as they've beaten them on the offensive boards in all three games. In Game 1 the differential was 14-12, in Game 2 it was 19-5, and in Game 3 it was 11-6. The C's only really paid for their lacking effort in their Game 3 loss, but another subpar rebounding performance could get them in trouble again.

Even Celtics point guard Marcus Smart recognized the importance of limiting the Hawks' second chances.

“There’s nothing tactical about it,” Smart said, per The Athletic's Jay King. It’s just a matter of will. And they wanted it more tonight. They go every night. We’ve gotta be able to stop that. Like I said, they’re getting second-chance shots, they get to feeling good.”

Improving on the glass doesn't necessarily require a specific tactic, but Boston could play center Robert Williams III more in order to snag more rebounds. He has yet to play over 23 minutes in a game this series and could really set the tone on the glass if he starts Game 4 or sees more minutes.

2. Establish a paint presence

The C's have made the 3-pointer their priority this season, yet that doesn't mean they should abandon the paint.

In Game 1, the Celtics matched the Hawks in that critical area, as they both scored 54 points in the paint. In Game 2, the C's put up 64 points in the paint to Atlanta's 40, which was one of Boston's best performances down low in franchise history.

During Game 3, the Green Team was connecting from deep with 21 triples, resulting in them settling on some shots and moving away from the paint. The Celtics are tough to beat when they hit their 3-pointers, yet they're nearly unstoppable when they dominate the paint at the same time.

Attacking there also requires driving to the hoop, which the Celtics will need to do more of in Game 4 if they want to avoid Game 3's rough ending.

1. Attack the pick-and-roll

The Hawks love the pick-and-roll. So much so that according to the league's advanced stats, they utilized it more than any other team over the course of the regular season:

When the C's aren't aggressive with the rolling player, whether it be Dejounte Murray, Trae Young, or whoever, they can pay the price. Boston will have to be more physical with the Hawks' pick-and=roll game and not sag too far off the rollers or screeners.

Of course, it's easier said than done, as committing too hard to physicality can lead to costly fouls that'll put Young and other great free throw shooters on the line. The Celtics will need to implement a sort of balancing act that disrupts Atlanta's pick-and-rolls without getting them in foul trouble.

The bottom line is drop coverage against Young is a problem.

Overall, following a rough Game 3, the Green Team has lots to work on. Whether or not they corrected their past mistakes will be on display Sunday in a significant Game 4.