The Indiana Pacers ousted the top-seeded Boston Celtics 109-101 in a Game 7 at TD Garden on Monday night, completing the deepest first-round upset of the NBA playoffs in more than a decade and leaving a bracket in which only three of the league’s top six regular-season seeds have advanced past the opening round. Tyrese Haliburton scored 34 points and added 11 assists, his fifth straight game with at least 30 and 10, and the Pacers held Jayson Tatum without a field goal across the final 6:42.

The result reverberated across a postseason calendar that has produced four series going to seven games, the highest first-round total since 2011, and a Western Conference picture in which the Los Angeles Lakers and Phoenix Suns will meet Tuesday night at Crypto.com Arena for a winner-take-all game of their own. The Lakers, behind 32 points from LeBron James and a 15-point fourth quarter from guard Austin Reaves, forced the deciding game with a 121-117 road win in Phoenix on Sunday, sending what James has confirmed will be his final postseason into at least one more contest.

“We didn’t get out-coached, we got out-played,” Celtics head coach Joe Mazzulla told reporters in a brief postgame availability in Boston. “Indiana was the better team in this series. They earned it on both ends of the floor, and I told them that in their locker room.”

Forward Jaylen Brown, who had been ruled out of Games 4 and 5 with a right hamstring injury, returned to the floor for Game 7 and played 28 minutes but finished 4 of 14 from the field for 11 points. Tatum, the East’s leading scorer in the regular season, scored 22 but shot 6 of 22 and committed five turnovers, three in the fourth quarter. The Celtics, who finished 62-20 and entered the postseason as championship favorites at most sportsbooks, became the second No. 1 seed to lose a first-round series in three years.

For Indiana, the win continued a stretch that has reset expectations around a roster built primarily around Haliburton, forward Pascal Siakam and a young supporting cast assembled by team president Kevin Pritchard. The Pacers will open a conference semifinal against the winner of Cleveland-Orlando, with the Magic leading 3-2 entering Game 6 in Cleveland on Tuesday night. Cavaliers guard Donovan Mitchell, asked Sunday whether his team had let a winnable series slip away, told reporters: “We’re not eliminated. Until we are, that question doesn’t apply.”

In the West, Phoenix forced its Game 7 behind a 41-point, nine-rebound performance from Devin Booker and a defensive scheme that bottled up Lakers center Anthony Davis, who was held to 12 points on 4-of-13 shooting. The Suns, who trailed the series 2-3 after losing Game 5 at home, have now won six elimination games over the past two postseasons, an active league high.

“We’ve made it harder than it had to be, but we’re still alive,” Suns head coach Mike Budenholzer said. “One game in their building. We’ve done it before, and we have to do it again.”

The Memphis Grizzlies, the West’s No. 5 seed, advanced past the Denver Nuggets in six games on Saturday after Nikola Jokic, returning from a left wrist sprain that cost him three games, scored 38 in a Game 6 loss at FedExForum. Grizzlies guard Ja Morant, who had been limited to 28 minutes per game across the regular season under a load-management protocol, played 41 minutes in the clincher and finished with 29 points and 12 assists. The Oklahoma City Thunder, who swept the Sacramento Kings in the round’s only four-game series, await the Grizzlies in a conference semifinal scheduled to begin Friday in Oklahoma City.

The Minnesota Timberwolves, the West’s No. 6 seed, eliminated the No. 4 Los Angeles Clippers in five games and will face the winner of Lakers-Suns. Houston, after splitting its first six games with Golden State, lost Game 7 at home Sunday afternoon when guard Jalen Green missed two free throws with 11 seconds remaining; the Warriors, behind 31 points from Stephen Curry, advanced and will meet either Phoenix or Los Angeles in the second round.

“Even people inside the league are having trouble keeping the bracket straight in their heads,” said Karen Maldonado, a sports-media analyst at MoffettNathanson. “When this many seven games come at the broadcasters in a single weekend, you start to see the calendar tighten in ways the conference finals will feel.”

The league announced Monday afternoon that the conference semifinal round will open no earlier than Friday, May 1, and that television windows would be finalized within 24 hours of the Lakers-Suns game. NBA Commissioner Adam Silver, in a brief statement, said attendance across the first round averaged 18,940, the league’s highest figure since the 2019 postseason, and that combined television viewership across ABC, TNT and ESPN platforms was running 19 percent above the comparable round last year.

Major League Baseball, meanwhile, has hardened the April standings table that surprised oddsmakers three weeks ago. The Detroit Tigers, at 18-7, opened a five-game lead in the American League Central; right-hander Tarik Skubal threw seven shutout innings against Cleveland on Sunday, dropping his ERA to 1.61 across six starts. The Cincinnati Reds, 17-8 and leading the National League Central, completed a three-game sweep of the Chicago Cubs at Great American Ball Park behind another four-hit day from shortstop Elly De La Cruz, who is now hitting .335.

The New York Yankees, 9-15 and last in the AL East, designated relief pitcher Tommy Kahnle for assignment on Monday and recalled left-hander Brent Headrick from Triple-A Scranton. Manager Aaron Boone, asked by reporters in the Bronx whether his job security had become a topic in the clubhouse, said only that the team’s focus was on a road series in Tampa beginning Tuesday. The Los Angeles Dodgers, 16-9, maintained a four-game NL West lead despite losing two of three to the San Francisco Giants over the weekend.

Caesars Sportsbook trader Renee Caldwell, reached by phone Monday, said futures markets had continued to shift around Detroit and Cincinnati. “Three weeks ago we said April was weather,” Caldwell said. “It’s now late April, and the recreational money has noticed.”

The NHL playoffs, in their second round, have produced a parallel set of upsets, with the Florida Panthers eliminated in five games by the Tampa Bay Lightning on Saturday and the Edmonton Oilers facing elimination Tuesday in their series against the Los Angeles Kings. League officials said additional second-round windows for both leagues would be announced before the end of the week.