Boston Celtics star Jayson Tatum has reportedly agreed a max rookie contract extension worth up to $195million.

Tatum's new five-year, $163m deal in Boston could rise to almost $200m, according to ESPN.

The 22-year-old – the third pick in the 2017 NBA Draft – led the Celtics to the Eastern Conference Finals last season, while earning his first All-Star appearance.

It was a coming of age for Tatum in 2019-20, much to the delight of the Celtics and all those connected with the team.

Tatum cemented himself as one of the best players in the league by averaging 23.4 points, 7.0 rebounds and 3.0 assists per game – up on his 2018-19 averages of 15.7ppg, 6.0rpg and 2.1 apg.

The Celtics forward also enjoyed a fine playoff campaign, becoming only the third player in NBA history to average 25.0-plus points, 10.0-plus rebounds and 5.0-plus assists per game in a single postseason with 15 or more games played.

Los Angeles Lakers superstar LeBron James (in 2014-15 and 2019-20) and Boston's Larry Bird (in 1983-84 and 1986-87) are the only other players to reach the feat.