The Indiana Pacers ended the Boston Celtics’ title defense in five games Sunday night with a 109-101 win at TD Garden, the first time the league’s top seed has been bounced in the first round since 2007 and a result that completes the most chaotic opening week of the NBA playoffs in more than a decade. Hours later in Los Angeles, LeBron James and the Lakers forced a Game 7 against the Phoenix Suns with a 122-115 win at Crypto.com Arena, leaving three of the league’s eight first-round series unresolved as the calendar turned to a second week of play.

Tyrese Haliburton finished with 28 points and 12 assists for Indiana, including 14 points in the fourth quarter, when the Pacers outscored Boston 32-21 to pull away from a one-point game with 9:11 to play. Jayson Tatum led the Celtics with 36 points but shot 3 of 12 from beyond the arc; Jaylen Brown, who had been a game-time decision after missing three games with a right hamstring strain, returned but logged just 22 minutes and was held to 11 points. The Celtics, who finished the regular season 62-20, had been -260 favorites at most sportsbooks to win the series after taking Game 1 in Boston a week ago.

“Their best two players were not their best two players in this series, and ours were,” Pacers head coach Rick Carlisle told reporters in the visitor’s tunnel at TD Garden. “Tyrese was the best guard on the floor every night, and Pascal Siakam gave us everything we asked. Boston is a great team. We were better in the moments that decided four games.”

The defeat triggered immediate questions about the Celtics’ offseason. Brown is eligible for a five-year supermax extension this summer that could exceed $345 million, and team president Brad Stevens, who declined to address roster matters at his postgame availability, is expected to meet with ownership in the coming days. Head coach Joe Mazzulla, asked whether he had spoken to Stevens after the loss, said only that the conversation “will happen, and it should.” Boston has now lost three of its last four playoff series after winning the 2024 championship.

In Phoenix, the Lakers staved off elimination behind a 41-point, 11-rebound performance from forward Anthony Davis, who shot 14 of 22 and protected the rim across the second half as Phoenix repeatedly attacked the basket. James added 26 points, eight rebounds and seven assists in 41 minutes; head coach JJ Redick said afterward that he had no plan to scale back his star forward’s workload for Tuesday’s Game 7 in Phoenix. “He told me before the game he wanted forty,” Redick said of James. “I told him he could have forty-two. We will figure out Tuesday on Tuesday.”

Devin Booker scored 33 for the Suns but was 0 for 6 from three in the fourth quarter, and Kevin Durant, who had been listed as questionable with a lower back contusion sustained in Game 4, did not play. Suns head coach Mike Budenholzer said Durant would be re-evaluated Monday morning and that his availability for Game 7 was “fifty-fifty, maybe better.”

The two Sunday games headlined a weekend in which the first round both narrowed and dragged. Minnesota completed a five-game upset of the No. 4 Los Angeles Clippers on Saturday afternoon at Intuit Dome, with Anthony Edwards scoring 36 and the Timberwolves closing the series after dropping Game 4. The Memphis Grizzlies, behind Ja Morant’s 32 points, beat the Denver Nuggets 108-103 in a Game 5 at Ball Arena played without Nikola Jokic, who remains sidelined with a left wrist sprain. That series, tied 3-2, will return to Memphis for Game 6 on Tuesday, with Game 7, if necessary, in Denver on Thursday.

The Cleveland Cavaliers, who fell behind Orlando 3-2 on Friday, forced a Game 6 Sunday afternoon with a 102-93 win at Kia Center, Donovan Mitchell scoring 35. Houston closed out Golden State in six games Saturday night at Toyota Center, with Jalen Green and Alperen Sengun combining for 60 points. The Atlanta Hawks finished their five-game series win over the Milwaukee Bucks on Saturday, with Giannis Antetokounmpo’s back soreness limiting him to a season-low 18 minutes in the final game.

“The league has never had a first round where four of the top six seeds were either out by Sunday or fighting for their lives on Tuesday,” said Karen Maldonado, a sports-media analyst at MoffettNathanson. “Whatever the second-round bracket ends up looking like, it will be the least chalk-driven set of series in the play-in era.”

NBA Commissioner Adam Silver, in a statement Sunday evening, said the conference semifinal schedule would be finalized within 24 hours of the last first-round game and that the league had asked broadcast partners ABC, ESPN and TNT to hold flexible windows through Thursday. Television ratings for the first round are tracking at their highest level since 2018, the league said, with the Sunday Pacers-Celtics game averaging 6.4 million viewers on ABC and peaking above 8 million in the fourth quarter.

Major League Baseball, in the background, provided its own April story. The Detroit Tigers, idle Sunday after a rainout in Cleveland, remained tied with the Baltimore Orioles atop the American League at 17-7. The Cincinnati Reds beat the Pittsburgh Pirates 6-2 behind seven shutout innings from Hunter Greene, holding their NL Central lead at three games. The New York Yankees lost their fourth straight, falling to 8-15 and last in the AL East; general manager Brian Cashman, speaking on a New York sports radio program Sunday morning, said the club was “not panicking, but we are paying very close attention to every game.” Left-hander Carlos Rodon, on the 15-day injured list with what the team called left forearm fatigue, threw a 25-pitch bullpen session at Yankee Stadium on Saturday.

The NHL playoffs, into their second round seeding window, will see the Florida Panthers open their conference semifinal Tuesday against the Toronto Maple Leafs. The NFL draft concluded Saturday in Pittsburgh, where the Tennessee Titans took Texas quarterback Quinn Ewers with the first overall pick, as widely expected.

League officials said Game 6 between Cleveland and Orlando is scheduled for Tuesday evening in Cleveland, with Lakers-Suns Game 7 and Grizzlies-Nuggets Game 6 also on Tuesday. The earliest the conference semifinals can begin is Friday, May 1, officials said, with most second-round series likely to open over the following weekend.