Oklahoma City Thunder guard Shai Gilberteous-Alexander has signed a five-year, $172million maximum rookie contract extension. His agent Thaddeus Foucher, of Wasserman, informed ESPN's Adrian Wojnarowski.A 30% escalator clause is included in the deal that will turn the $172 million guaranteed base into $207 millions if Gilgeous-Alexander is elected to one of three All-NBA teams. There are no early termination options.Gilgeous-Alexander (23), is an integral part of the Thunder's future rebuilding as he develops to be a potential All-Star-caliber point-guard. In 2018, the LA Clippers drafted him 11th overall. He was then acquired by Oklahoma City as part of the 2019 trade that brought Paul George to LA. He has improved steadily season to season, becoming a skilled shooter and one the most effective isolation scorers in NBA. He was already a top attacker and led the NBA in drives per games (25.2) last year.Gilgeous Alexander took over as the Thunder's primary option, replacing Chris Paul in Phoenix. It was a great season. Averaged 23.7 points per game on 50.8% shooting from floor, 41.8% shooting from 3-point range, and 80.8% from free throw line. Plus, 5.9 assists, 4.7 rebounds, and 53.7 points.Gilgeous-Alexander had to have his season cut short by a serious plantar fasciitis tear. His absence in March caused the Thunder to change the course of their season. They switched to younger players and hoped for a better draft pick. The Thunder went 16-19 with Gilgeous-Alexander; they were 6-3 without him.Gilgeous-Alexander is a key player in the Thunder's future as they reposition their roster. Young players include 2021 No. As Sam Presti retools the roster, Gilgeous Alexander is a solid foundation. He has a 6th overall pick Josh Giddey, and Lu Dort.This report was contributed by ESPN's Royce Young.