The Boston Celtics, Washington Wizards and Memphis Grizzlies agreed to a three-team trade late Wednesday night that sent center Kristaps Porzingis to the Celtics, guard Marcus Smart to the Grizzlies and guard Tyus Jones to the Wizards, sources told ESPN's Adrian Wojnarowski.

As part of the deal, Memphis is sending Boston its first-round pick in Thursday's draft -- the 25th overall selection -- as well as the Golden State Warriors' top-four-protected first-round pick in 2024, sources said, while the Celtics are sending the 35th pick in Thursday's draft to Washington. The Celtics are also sending forward Danilo Gallinari and center Mike Muscala to Washington as part of the deal, sources said.

The three-team deal came together in the minutes leading up to a midnight ET deadline for Porzingis to opt in to his $36 million player option for the 2023-24 season. With the deal completed, Porzingis did opt in, sources said.

The trade capped a long day of negotiations involving the Celtics and Wizards over a possible Porzingis deal, after the two teams first attempted to hammer out a three-team agreement with the LA Clippers that would've sent Malcolm Brogdon to Los Angeles, the 30th pick in the draft to the Wizards and Porzingis to the Celtics.

But when that deal fell apart, Boston pivoted to talks with Memphis, allowing this deal to come together just before the deadline.

For the Celtics, the deal presents a radical shift in what their team will look like.

Porzingis, who will turn 28 on Aug. 2, had arguably the best season of his NBA career this past year in Washington, averaging a career-high 23.2 points to go along with 8.4 rebounds, 2.7 assists and 1.5 blocks in 65 games for the Wizards. The fourth overall pick in the 2016 NBA draft by the Knicks was playing his first full season in Washington after the Wizards traded for him at the 2022 trade deadline, sending Spencer Dinwiddie and Davis Bertans to Dallas in exchange.

Now, he is off to Boston, where the Celtics are attempting to retool their roster to make another run at an 18th NBA championship this coming season, as Porzingis will give the Celtics an entirely different offensive dimension alongside stars Jayson Tatum and Jaylen Brown, in addition to the Celtics landing those two first-round selections.

Landing Porzingis was just the first of several big decisions ahead for the Celtics this summer, as Boston also can offer Brown, an All-Star forward, a five-year, $295 million contract extension this summer and has to sort out the future of restricted free agent forward Grant Williams.

Boston will also have to adjust to life without Smart, who has been the heart of the team throughout his nine years with the franchise, making him the longest-tenured player on the current roster in addition to being one of the league's best and most versatile perimeter defenders, which was recognized by his winning the 2022 Defensive Player of the Year award.

But all of the things that made Smart so valued in Boston are exactly what the Grizzlies will be looking for him to provide in Memphis, as they try to bounce back from last year's first-round exit against the Los Angeles Lakers. Smart, who averaged a career-high 6.3 assists last season for the Celtics, will also be more than capable of stepping into the starting point guard role for Memphis while Ja Morant is serving his suspension over the first 25 games of the season.

It had been anticipated that Jones was going to be the player filling in for Morant. Instead, Jones will now be the starting point guard in Washington, where new president of basketball operations Michael Winger continues to remake the team's roster.

This is the second significant trade the Wizards have made in the space of a few days, after completing the blockbuster deal to send Bradley Beal to the Phoenix Suns on Sunday for Chris Paul, Landry Shamet, several second-round picks and first-round pick swaps.

Meanwhile, sources told Wojnarowski on Tuesday that Washington forward Kyle Kuzma, one of the more intriguing free agents on the market this summer, declined his player option and will be an unrestricted free agent.