One down, two to go. The Nets took the first step toward trying to escape from a 3-1 deficit in their first-round series against the Bulls with a 110-91 victory in Game 5 in front of a sellout crowd of 17,732 at Barclays Center in Brooklyn. The series now shifts back to Chicago for Game 6 on Thursday, as the Nets try to become the ninth team in NBA history to recover from down 3-1 in a best-of-seven series. “We have to stay aggressive,” said Gerald Wallace, who finished with 12 points — including five in a quick burst with about two minutes remaining that sealed the win. “Right now, it’s win or go home. Like the coaches say, we’re in an NCAA Tournament right now, so every game counts, every possession counts. “We just have to come out and play hard. … I don’t think any of the guys are ready to go home yet.” It was unclear whether the Nets would be able to recover from allowing a 14-point lead with three minutes remaining in Game 4 to slip away following a scoring explosion from Bulls guard Nate Robinson and eventually losing in triple-overtime. But the Nets said before the game last night they had gotten over the loss, then went out and looked like a team with a point to prove, riding yet another hot start from Brook Lopez — who had 11 points and three rebounds in the opening quarter — to jump out to a 26-21 lead after one. Lopez, the team’s lone All-Star who also is making his first postseason trip, finished the game with 28 points and 10 rebounds, and now has scored at least 20 points in all five games in the series. “He has players around him now who match his intensity and make him want to match that,” Reggie Evans said. “And not only that, he has players who have his back. He has players that encourage [him] like, ‘You’re going to make the All-Star [Game] this year.’ … [If you] hear it so much, you eventually start doing it.