BOSTON – The Boston Celtics’ new Big Three will stay together to try for a second NBA title.

Ray Allen confirmed Wednesday night that he agreed to a two-year, $20 million contract to return to Boston. With Kevin Garnett under contract, Paul Pierce on the verge of a new four-year deal and Coach Doc Rivers also agreeing to return, the Celtics can keep together the core of the 2008 NBA champions for at least two more years.

Allen’s agent, Lon Babby, said the second year is a player option. NBA teams are not allowed to sign free agents until today.

The deal was first reported by ESPN.

Allen, who turns 35 this month, averaged 16.3 points last season as the Celtics reached the NBA finals for the second time in three years. After Boston lost to the Los Angeles Lakers in seven games, Allen said, “It’s obvious I don’t want to be anywhere else.”

Allen joined the Celtics in the summer of 2007, joining with Pierce to lure Garnett to Boston to form a new Big Three that won an NBA title in its first season together. The next year, with Garnett injured, the Celtics lost in the Eastern Conference semifinals.

With the team struggling at the All-Star break this year, General Manager Danny Ainge considered trading Allen and trying to make the team younger by rebuilding around point guard Rajon Rondo. Instead, Ainge kept the core together and it rewarded him by returning to the finals.

Allen was inconsistent against the Lakers, hitting an NBA finals-record eight 3-pointers in Game 2, then going 0 for 16 from 3-point range over the next three games. But Rivers never wavered in his support, praising Allen’s defense and also the way he forces opponents to cover him wherever he is on the floor, opening up space for his teammates. 

HEAT: Ending months of speculation, Dwyane Wade and Chris Bosh announced that they’ll sign with Miami.

Wade told the Heat that for him to re-sign, the team had to add Bosh or LeBron James.

“It had to be one or the other,” Wade said. “Of course, there’s a lot of talented players in this league. But you want to look at players that complement my game, and Chris and LeBron are two of those guys.” 

BULLS: Two-time All-Star forward Carlos Boozer agreed to a deal with Chicago, a person familiar with the negotiations said, speaking on the condition of anonymity because the contract doesn’t become official until today. 

CLIPPERS: Los Angeles introduced Vinny Del Negro as its head coach. Del Negro, fired by the Bulls two months ago, takes over a team that was 29-53 last season.

He replaces Kim Hughes, who finished the season as interim coach after Mike Dunleavy stepped aside in February to focus on his GM duties before leaving for good in March. 

KINGS: Sacramento signed rookie center DeMarcus Cousins to a contract. Cousins can earn about $7 million in the first two years, and the Kings have separate team options for the third and fourth seasons. 

THUNDER: Kevin Durant agreed to a five-year contract extension with Oklahoma City, he posted on his Twitter page. 

SALARY CAP: The NBA salary cap for next season was set at $58.04 million, a higher number than projected.

The cap went into effect at 12:01 a.m. today, ending the league’s moratorium period and allowing free-agent contracts to be signed.