The most anticipated second-round matchup of the NBA playoffs opened with a thud Saturday night when James Harden suffered a right hamstring injury in the opening minute of the Brooklyn Nets’ 115-107 victory over the Milwaukee Bucks.

Harden, who was among the leading MVP candidates before missing 21 games in April and May with a right hamstring strain, appeared to suffer the injury while driving to the basket in transition. The nine-time all-star grabbed at the back of his right leg and then departed for the locker room after asking Nets Coach Steve Nash to take a timeout. Brooklyn announced before halftime that Harden would not return to Game 1, and he departed Barclays Center early to undergo an MRI exam.

“I didn’t realize what had happened until [Harden] started walking off the court,” Nets forward Kevin Durant said. “It just sucks. I want him to be out there. I know how much he cares. I know how much he wants to be in this moment. I’m wishing him a speedy recovery, and we’ll keep him involved as much as possible. It’s just a bad break.”

The 31-year-old Harden averaged 24.6 points, 7.9 rebounds and 10.8 assists this season, which saw him move from the Houston Rockets to the Nets in a January blockbuster trade. Brooklyn, the East’s second seed, went 29-7 with Harden in the lineup and 19-17 without him during the regular season.

But Brooklyn quickly steadied itself after Harden’s departure. Durant tallied a team-high 29 points, plus 10 rebounds and three assists, and Kyrie Irving added 25 points, five rebounds and eight assists. The Nets were able to play at their preferred tempo and generated high-percentage looks against a Bucks defense that had stifled the Miami Heat in the first round.

Nash has juggled his lineups all season, with Durant, Harden and Irving missing extended stretches at various points. In Game 1, Brooklyn turned to backup guard Mike James, who scored 12 points in 30 minutes after playing just 10 minutes over five games in the first-round series victory against the Boston Celtics.

“We’ve had a lot thrown at us this year,” Nash said, noting during his news conference that the severity of Harden’s injury was not yet known. “We’re, in a sense, well trained for this event. You never want to see that. Someone like James, who is such an important player, such an incredible player, he cares so much.”

Brooklyn’s first-year coach added that it was “tough” to adjust so early in the game without Harden and that he was “proud of the guys that they didn’t get rattled.”

“When you see the game get snatched away from one of our brothers, you feel for him,” Irving said. “We came in the huddle, made sure that everybody on the bench knew the situation we were in, and we just played it out from there. It went our way tonight, but we’re going to feel his loss no matter what.”

Giannis Antetokounmpo led Milwaukee with a game-high 34 points to go with 11 rebounds and four assists, but he committed five turnovers and attempted just three free throws. Bucks forward Khris Middleton struggled from the field, making 6 of 23 shots to finish with 13 points. As a team, the Bucks made only 6 of 30 three-point attempts.

Game 2 is set for Brooklyn on Monday.

After failing to reach the Finals during eight years in Houston, Harden is seeking the first championship of his career with Durant, Irving and the Nets. To this point, he has enjoyed impeccable health in his postseason career. Harden has appeared in 134 playoff games over 12 postseason runs, never missing a game because of injury.

The 2018 MVP averaged 27.8 points, 7.2 rebounds and 10.6 assists in the first round against the Celtics, who finished the series without several injured players, including Jaylen Brown and Kemba Walker.

“I’ve been in the other situation a lot,” Harden said after eliminating the Celtics. “To where I dealt with injury [and] dealt with guys going out late in the series. I’ve dealt with that. I’ve been on that team. At the end of the day, nobody really cares. Nobody cares who is injured. All that matters is the win. This is how it is, and so we’ll take it.”

Milwaukee, the East’s third seed, entered the Eastern Conference semifinals without guard Donte DiVincenzo, who suffered a season-ending ankle injury during a first-round sweep of the Heat.