Phoenix Suns restricted free agent center Deandre Ayton is signing a four-year, $133 million maximum contract offer sheet with the Indiana Pacers, his agents, Bill Duffy and Nima Namakian, told ESPN on Thursday.

The Suns have two days to match the largest offer sheet in NBA history and keep Ayton -- or let him go to the Pacers for nothing in return.

Ayton's offer sheet surpasses the four-year, $107 million deal signed by Otto Porter Jr. with the Brooklyn Nets in 2017 -- a deal the Washington Wizards ultimately matched.

Sign-and-trade deals are no longer allowed once Ayton signs the offer sheet with Indiana.

So far, the Suns haven't shown an interest in negotiating a sign-and-trade with the Pacers, but the expectation remains that Phoenix will match the record $133 million offer sheet once it's signed by Ayton, sources told ESPN.

If the Suns do match the offer sheet, they can't trade Ayton anywhere until at least Jan. 15 -- and can't trade him to Indiana for a year. Ayton will also have veto power on any trade for a year.

Namakian of Innovate Sports and Duffy of BDA Sports and WME had insisted to the Suns that they could find a maximum contract offer for Ayton in the marketplace, and they are now delivering it with the offer sheet. The Suns had never made Ayton a max offer, suggesting they didn't value him as a max player. If they don't match the sheet, the Suns will lose the 2018 No. 1 pick without compensation.

The biggest offer sheet signed by a team that wasn't matched was when Harrison Barnes was signed by the Dallas Mavericks for four years and $94.4 million in 2016, the same summer when Barnes' former team, the Golden State Warriors, signed Kevin Durant as a free agent.

Ayton has been enthusiastic about the possibility of pairing with talented young guard Tyrese Haliburton and becoming a centerpiece of the Pacers' rebuild, sources told ESPN.

Indiana traded Malcolm Brogdon earlier this offseason and Domantas Sabonis last season, shifting into a new era centered around an exciting young backcourt of Haliburton, an emerging star, and rookie Bennedict Mathurin, the sixth pick in last month's NBA draft.

The Pacers would have to clear out $4.7 million in cap space to sign Ayton to the max offer sheet. To do that, Indiana is waiving guard Duane Washington and waiving and stretching the three players who arrived in the Boston trade for Brogdon: Malik Fitts, Juwan Morgan and Nik Stauskas, sources told ESPN.

Ayton, who turns 24 next week, was drafted with the first pick in the 2018 draft out of Arizona, part of a star-studded draft class that also included Luka Doncic (third), Jaren Jackson Jr. (fourth), Trae Young (fifth) and Shai Gilgeous-Alexander (11th).

After making the All-Rookie first team in 2019, Ayton has developed into a quality starting center, averaging 16.3 points and 10.5 rebounds while helping anchor Phoenix's defense during its run to the 2021 NBA Finals -- the first time the franchise had reached the league's championship round since Charles Barkley led the Suns there in 1993.

He averaged 17.2 points and 10.2 rebounds this past season, shooting 63.4% from the field and 74.6% from the foul line.

After an outstanding regular season, finishing with the league's best record, Phoenix's postseason ended with a blowout loss to the Mavericks in Game 7 of the Western Conference semifinals -- a game Ayton spent most of the second half watching from the bench.

When asked after the game why that happened, Suns coach Monty Williams said, "It's internal." Ayton, meanwhile, declined to talk to reporters after the game.

ESPN's Tim Bontemps and Bobby Marks contributed to this report.