The Boston Celtics were left to wonder what might have been after a poor third quarter saw them lose Game 2 of the NBA Finals against the Golden State Warriors on Sunday, levelling the series at 1-1.

An underwhelming first half performance saw the Celtics trail by only two points, and after their incredible fourth quarter showing in Game 1, the hope for Boston was they could finish strongly again and take a commanding 2-0 lead.

However, after finding themselves trailing by 23 points by the time the final quarter arrived, they had left themselves far too much to do.

Celtics coach Ime Udoka blamed the amount of turnovers, saying after the 107-88 defeat at Chase Center: "That's been an ongoing theme in the playoffs so far. We've turned over the ball. Take teams out of scoring against us in the half court, give them some baskets.

"But it was more of the same in that third quarter. We had 11 for 18 points in that first half and gave up five or six more in that quarter. Kind of blew it open, and that hampered our offense, as well."

Jayson Tatum - who top-scored for the Celtics with 28 points, though ended the game with a minus-36, which is the worst plus-minus of the 24-year-old's career - agreed with Udoka on turnovers, but also pointed to the general sloppiness at the start of the third-quarter that saw the Warriors pull away.

"I think tonight, turnovers, and I think sometimes letting our offense affect how we defend, kind of was a little stagnant in the third quarter," Tatum said.

"I feel like it translated on the defensive end, and they got going and hitting shots and things like that."

Boston have now been outscored by at least 14 points on four occasions in the third quarter during this year's playoffs, and guard Derrick White also expressed his frustration at the increasing trend of losing the game just after half-time.

"Yeah, it's definitely frustrating," he said. "I mean, we've talked about it pretty much the whole postseason. It's easy to talk about, but we've got to go out there and change something.

"That was a big quarter for them and really a quarter that put us away."

The Boston Celtics smothered the Miami Heat all night on the way to a 102-82 victory in Game 4 of the Eastern Conference Finals.

With the win, the Celtics evened the series at 2-2, and are still yet to lose back-to-back games this postseason. 

It all started on the defensive end for Boston, playing in front of their raucous home fans, as the Heat missed their first 14 field goal attempts.

The Celtics led 29-11 at quarter time – after leading 26-4 at one stage – marking the fewest first-quarter points ever scored by a Heat team in the playoffs. They shot three-for-20 from the field.

Victor Oladipo tried to ignite the Heat off the bench, scoring 18 of their first 28 points, but it was a historically bad showing from Miami's starting line-up, made even worse by the fact Sixth Man of the Year Tyler Herro was out injured.

With three minutes remaining in the third quarter, the Heat trailed 73-42, leading to their starters getting benched for the final frame. Their five starters combined to score 18 points and shoot seven-for-38 (18 per cent) from the field.

For Boston, Jayson Tatum was terrific, scoring 24 of his 31 points in the first half, finishing up with shooting figures of eight-of-16 from the field and 14-of-16 from the free throw line.

The big-man combination of Al Horford and Robert Williams III was also game-changing, as the duo combined for 22 rebounds and six blocks, while Derrick White also shined in his first game since becoming a father.

White missed Game 3 for the birth of his child, and after scoring no more than nine points since Game 4 of the Celtics series against the Milwaukee Bucks, he had 10 points in the first quarter as he started in the place of the injured Marcus Smart.

He went on to finish with 13 points, eight rebounds, six assists, three steals and a blocked shot.

Game 5 will head back to Miami with plenty on the line. Throughout NBA history, when a series has been tied 2-2, the winner of Game 5 goes on to win the series 82 per cent of the time – although the Celtics bucked that trend last round.

The Philadelphia 76ers solved their Ben Simmons conundrum with a blockbuster trade for James Harden of the Brooklyn Nets before the NBA trade deadline passed on Thursday. 

Simmons has refused to play for the Sixers this season after coach Doc Rivers and center Joel Embiid were critical of his performances in the Eastern Conference semifinals loss to the Atlanta Hawks last season. 

Philadelphia had been trying to trade the fifth-year guard/forward ever since, but the former Rookie of the Year's value plummeted after he came up short against the Hawks. 

However, according to multiple reports a deal was finally struck to send Simmons to Brooklyn in exchange for the 2018 NBA MVP Harden. Seth Curry, Andre Drummond, an unprotected 2022 first-round pick and a protected 2027 first-round pick were also sent to the Nets, with Paul Millsap going in the opposite direction. 

Harden can become a free agent in the offseason, while Simmons is under contract until 2025 after signing a five-year, $177.2million deal in 2019.

While the 76ers seemingly boosted their chances of contending by adding Harden, the Los Angeles Lakers and Golden State Warriors remained idle. However, there were still plenty of other deals reported on Thursday.

Mavericks move on from Porzingis

The Luka Doncic-Kristaps Porzingis era is over in Dallas.

The Mavs sent Porzingis and a second-round pick to the Washington Wizards in exchange for Spencer Dinwiddie and Davis Bertans.

Injuries have continued to trouble the 7ft 3in center, who averaged 20 points and 8.8 rebounds per game in two and a half seasons in Dallas.

Kings trade Bagley, Bucks get Ibaka 

The Sacramento Kings made Marvin Bagley III the second overall pick in the 2018 draft but brought an end to his time in California as part of a seven-player, four-team trade. 

Bagley was sent to the Detroit Pistons, with Josh Jackson and Trey Lyles going to Sacramento. The Kings also received Donte DiVincenzo from the Milwaukee Bucks, who swapped Serge Ibaka for Semi Ojeleye and Rodney Hood. The reigning NBA champions also received two future second-round picks and cash considerations. 

Bagley has started just 17 games for Sacramento this season, averaging 9.3 points and 7.2 rebounds in 21.9 minutes per game.

Celtics bring Theis back, send Schroder to Houston

Daniel Theis is back for a second spell with the Boston Celtics.

Less than a year after he was traded to the Chicago Bulls by the Celtics, Theis was brought back from the Houston Rockets in exchange for Dennis Schroder, Enes Freedom and Bruno Fernando. Freedom is expected to be waived by the Rockets, though.

Boston also sent Bol Bol and PJ Dozier, who are both out for the season, to the Orlando Magic and offloaded Josh Richardson and Romeo Langford to the San Antonio Spurs. The Celtics' brought in Derrick White.

Elsewhere...

Goran Dragic's time with the Toronto Raptors is up after he was traded to the Spurs for Thaddeus Young, Drew Eubanks – whom they were set to waive – and a 2022 lottery-protected first-round pick. Dragic is expected to be bought out, with the Chicago Bulls, Mavs, Bucks, Warriors, Nets and Clippers all credited with an interest.

The Charlotte Hornets added Montrezl Harrel from the Wizards. Ish Smith and Vernon Carey Jr went the other way. 

Torrey Craig is back with the Phoenix Suns following a deal that saw Jalen Smith land with the Indiana Pacers. Aaron Holiday was also acquired from the Wizards.