The Phoenix Suns and center Deandre Ayton failed to reach a deal on a contract extension ahead of a Monday deadline, ESPN's Adrian Wojnarowski reports.

Without a deal, the No. 1 pick in the 2018 draft will enter next offseason as a restricted free agent. The Suns could retain Ayton, but will be required to compete with qualifying offers from other teams.

Ayton sought a max extension in negotiations, and Suns owner Robert Sarver continued to decline to offer one ahead of Monday's deadline, per the report. The news puts a damper on the excitement around the start of Phoenix's season on the heels of last season's unexpected run to the NBA Finals.

Deandre Ayton key in Suns NBA Finals run

In three seasons in Phoenix, Ayton's averaged 16 points, 10.6 rebounds and 1.2 blocks per game while shooting 58.5% from the field. With the addition of Chris Paul to the roster, the Suns looked less to Ayton to score last season as he averaged 14.4 points per game. But he was a more efficient scorer and effective all-around player while shooting 62.6% from the field. He was critical in Phoenix's run to the Finals while averaging 15.8 points and 11.8 rebounds while shooting 65.8% from the field.

Ayton was eligible for a five-year, $172.5 million extension with incentives that could raise the value to $207 million. He's slated to make $12.6 million this season on the last season of a four-year, $40.3 million deal he signed as a rookie. The Suns reportedly floated the idea of three-year or four-year max deal but never formally made those offers, per the report.

Where Ayton's 2018 rookie classmates stand

Monday at 6 p.m. ET was the deadline for members of the 2018 draft class to sign extensions on their rookie contracts. Other top players from Ayton's class Luka Doncic, Trae Young, Michael Porter Jr. and Shai Gilgeous-Alexander have all signed max extensions.

Suns ownership reportedly doesn't believe that Ayton is on the same tier as players like Doncic and Young, who have been named All-Stars since joining the league. While Ayton's an efficient scorer, he doesn't possess the 3-point shooting prowess that's coveted in modern NBA big men. He's made seven 3-point shots in three seasons. This assessment bothers Ayton, according to the report.

Jaren Jackson Jr., the No. 4 pick in the 2018 draft, reportedly agreed to a deal less than the max on Monday valued at $105 million over four seasons. Jackson is a promising two-way big man with outside range, but is coming off missing most of last season with a knee injury.

Report: Landry Shamet, Suns reach 4-year, $43 million extension

Though Ayton isn’t getting his deal, Landry Shamet seems to have locked down his extension before the deadline.

The Suns and Shamet agreed to a four-year, $43 million extension on Monday afternoon, according to ESPN’s Adrian Wojnarowski.

Shamet was traded to the Suns from the Brooklyn Nets in August, where he averaged 9.3 points and 1.8 rebounds per game last season. The 24-year-old was set to enter the final year of his four-year, $9.5 million deal this season.