LaMarcus Aldridge and the San Antonio Spurs have at times seemed an ill-fitting pair, with a player who spent nine years in another franchise before landing with Gregg Popovich not always looking comfortable in the NBA's most well-established system.

The kinks the two sides have been trying to work through had league observers believing Aldridge might not be long for San Antonio. Just as they have for more than 20 years, the Spurs care little about what others think.

Aldridge and the Spurs reached agreement on a three-year extension on Monday that ensures the five-time all-star will be under contract through the 2020-21 season. The agreement involves Aldridge exercising the 2018-19 player option on the original four-year max deal he signed with the Spurs in 2015. He then will get another two years and $50 million tacked on to the deal, a person with knowledge of the agreement told The Associated Press.

ESPN first reported the agreement.

When the Spurs beat out the Suns, Lakers and several other suitors for Aldridge two summers ago, it was a departure from the franchise's long history of drafting and developing its stars. With Tim Duncan nearing retirement and Kawhi Leonard emerging as the team's next focal point, the Spurs splurged for Aldridge in free agency to try to extend the team's window for competing in the Western Conference.

He came from Portland, where he had spent years as the No. 1 option for the Trail Blazers, a formidable low-post presence with a strong mid-range game. Aldridge was an all-star in his first season in San Antonio, but his individual numbers declined significantly. That was to be expected in San Antonio's system, which emphasizes ball movement and tries to limit minutes to keep veterans fresh for the post-season.

Last year, Aldridge averaged 17.3 points and 7.3 rebounds per game, both career lows. But the Spurs won 61 games and advanced to the Western Conference final, where they were swept by the Golden State Warriors after Leonard injured his ankle in Game 1.

The 32-year-old Aldridge and Popovich met this fall to try to find ways to make him feel more comfortable and effective. The dialogue helped strengthen their relationship, made Aldridge feel open to staying in San Antonio and gave the Spurs the peace of mind that they could continue to feature him as a much-needed supporting star for Leonard.