Atlanta United has two shutouts in its three playoff games.

The most recent came in Sunday's 3-0 victory over New York Red Bulls in the first leg of the Eastern Conference finals at Mercedes-Benz Stadium.

Of course, it’s hard to score if it’s hard to shoot.

In those three playoff games this season, Atlanta United has allowed the following shots on goal: zero at Yankee Stadium in a 1-0 win over NYCFC, three in the second leg that was won by Atlanta United 3-1, and one to New York Red Bulls on Sunday.

Those two teams combined for 121 goals during the regular season.

“That was the change that we made after the Toronto game heading into the playoffs,” Atlanta United manager Gerardo Martino said. “We knew that we had to be solid defensively. We knew going into the playoffs it was going to be very important to be able to keep clean sheets. And that’s what we tried to do. And we’ve played three games now against top teams in the Eastern Conference, and we’ve held them to one goal. So, we knew that was going to be key.”

Atlanta United was good defensively during the regular season.  It allowed 44 goals, second-fewest in the East.

But the defense found a new gear following the 2-0 loss at New York Red Bulls in late September and the 4-1 loss at Toronto in the regular-season finale.

Part of the improvement was a new sense of urgency.

“When we were up in New York, we weren’t even on the same level as them and between that result and the result in Toronto that really lit a fire under us in terms of knowing we need to compete,” Atlanta United goalkeeper Brad Guzan said. “We needed to compete just everywhere, and today, we did that. We played the way we are able to play. We fought we battled and ultimately, we scored three great goals.”

Part of the improvement has been Martino’s decision to switch back to the 3-5-2/5-3-2 formation that worked well for a long stretch during the regular season. The formation gives the team the flexibility to put as many as nine players behind the ball on defense.

The team went away from the formation, to a 4-2-3-1, when midfielder Darlington Nagbe suffered an adductor injury in the middle of the season. His return allowed Martino to incorporate the formation again.

Its discipline on defense in pressuring passers and clogging passing lanes choked off attack after attack by NYCFC and then by Red Bulls, which feature two of the greatest scorers in MLS history in David Villa and Bradley Wright-Phillips, respectively.

“I think that we’ve just raised our game a little bit,” Atlanta United captain Michael Parkhurst said. “We’ve raised the energy, the desire, the fight. We’re not afraid to go out there and lose the possession battle. We don’t have to connect 30 passes to go to goal. We’re going to take what the game gives us and against the Red Bulls, a lot of the time, it’s play along, win 50-50s, get in behind them, quick attacks, so we did a little bit of that against New York City, as well. So, you have to adapt, and that’s what we’ve done well.”

Atlanta United will need to keep its intensity and discipline in the second leg of the series on Thursday. Though the Red Bulls scored 62 goals during the regular season, it has scored three goals at home just twice since June 23.

“At home, we are very confident,” Red Bulls midfielder Sean Davis said. “We love playing at home in front of our fans and we have been great there all year. It is important for us to get a first goal early, and then press for the game. It is going to require absolutely everything from us to get the result.”