Philadelphia, Pennsylvania - Paul George is joining the Philadelphia 76ers and Klay Thompson is heading to the Dallas Mavericks, multiple reports said Monday as NBA free-agency got into full swing.

Nine-time All-Star George is joining the Sixers on a four-year deal worth $212 million while Thompson, whose exit from the Golden State Warriors was confirmed on Sunday, has agreed terms on a three-year $50 million contract with Dallas, ESPN reported.

The two deals bolster the Sixers' and Mavs' championship aspirations, with George set to form a big three alongside Joel Embiid and Tyrese Maxey, and Thompson linking up with Luka Doncic and Kyrie Irving in Dallas.

Thompson is widely regarded as one of the greatest shooters in basketball history, forming a potent back-court partnership alongside Stephen Curry and featuring prominently in the Warriors' NBA championship-winning seasons in 2015, 2017, 2018, and 2022.

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George (34) has averaged 20.8 points, 6.3 rebounds, 3.7 assists, and 1.7 steals a game over 867 career contests in 14 seasons for Indiana, Oklahoma City, and the Los Angeles Clippers, whom he left behind last weekend after five seasons.

NBA clubs have a signing moratorium on finalizing all contracts until Saturday, so it's left to media reports to chart the moves that cannot yet become official.

George's coming to terms was reported by the Philadelphia Inquirer, The Athletic, and ESPN through unnamed sources.

The 76ers have not advanced beyond the Eastern Conference semi-finals since 2001 but might have their best chance with George joining All-Star guard Tyrese Maxey and Cameroonian star center Embiid, the 2023 NBA Most Valuable Player.

Multiple reports on Monday also had Maxey signing a five-year maximum contract extension worth $204 million. Maxey averaged 25.9 points and 6.2 assists for the Sixers last season.

George declined a $48.8 million deal for next season with the Clippers to test his value on the free agency market.

The 76ers also reportedly have struck a two-year deal worth just over $10 million with center Andre Drummond, a 12-year NBA veteran and five-seasons league rebounding leader.

Tobias Harris, a forward who played the past six seasons in Philadelphia, is reportedly off to the Detroit Pistons on a two-year deal worth $52 million.

Boston Celtics star Jayson Tatum, who sparked the club to the NBA title this season, has agreed to terms on a five-year supermax contract extension worth $315 million, according to TNT and ESPN.

It would be the largest deal in NBA history at an average of $63 million per year.

Tatum, who helped the US Olympic team win Tokyo gold and will seek a repeat crown at Paris, averaged 26.9 points, 8.1 rebounds, and a career high 4.9 assists for Boston this season.

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The move comes five days after the reigning NBA champions agreed to a deal worth $286.2 million over five years with Jalen Brown.

Derrick White has agreed to a four-year deal worth $125.9 million to stay with the Celtics, who extended Jrue Holiday for four years at $135 million three months ago.

Boston has also secured center Kristaps Porzingis, who opted into a $36 million salary for the 2024-25 campaign before a two-year extension worth $60 million begins.

The deals mean the Celtics will face limitations on what future deals they can make under tax apron salary limitations.

Center Isaiah Hartenstein, according to multiple reports, will leave New York for a three-year deal worth $87 million with the Oklahoma City Thunder, who also reportedly struck deals with reserves Aaron Wiggins and Isaiah Joe.