Spurs Coach Gregg Popovich said earlier this week that he doesn't know the answer to what his plans are for next season. (Brandon Dill/Associated Press)

The list of NBA coaches to win five titles is short and legendary: John Kundla, Red Auerbach, Pat Riley, Phil Jackson and Gregg Popovich. And it seems Popovich, the third-winningest coach of all-time and the only member of the five-title club still walking the sideline, is at least considering the end of his NBA coaching career.

On the heels of Wednesday night’s 105-101 Spurs win over the Mavericks in Dallas, Popovich, who is in the final season of a five-year contract, was asked by the New York Times’ Marc Stein about his plans for 2019-20.

“I don’t know the answer,” he responded.

And with that, we’re off and running on the Pop speculation train. Spurs General Manager R.C. Buford told Stein that Popovich will “coach as long as he wants to,” and that makes perfect sense. Popovich is the widely considered the best coach in the NBA and has only Jackson to compete with for the honor of best coach of the century. Popovich’s Spurs teams have won five championships since the lockout-shortened 1999 season, and one could make the case that he should have won a sixth were it not for the Heat’s Ray Allen making one of the most clutch shots of all time in Game 6 of the 2013 Finals.

But Popovich, who lost his wife last spring to a respiratory illness, will turn 70 later this month. And it’s not as though he has anything left to prove.

Last season proved to be one of the more difficult ones endured by the Spurs in their 20-year run as a marquee franchise. Superstar Kawhi Leonard shot his way out of town after bristling at the team’s diagnosis of a mysterious quad injury that hampered him all season. Leonard’s absence was a season-long soap opera, bringing drama to a team that never, ever experiences it.

Aside from the issues with Leonard, the aging Spurs seemed at times to have been left behind as the league became more pace-heavy and three-pointer obsessed. The Spurs maintained their usual standard of excellence on defense last season, ranking third overall in defensive efficiency. But they ranked 28th in pace, 27th in three-pointers attempted and 28th in three-pointers — and despite a 47-35 regular season (the first time they failed to win 50 in a full season under Popovich), they were bounced out of the playoffs in the first round by Golden State.

Things have solidified this season after a rocky start adjusting to the departure of Leonard, who was traded last summer to the Toronto Raptors along with Danny Green for DeMar DeRozan, Jako Poeltl and a first-round pick. San Antonio has won 15 of its past 21 games to move into the sixth seed in the ultracompetitive Western Conference.

Stein reminds that Popovich is committed to taking over USA Basketball’s men’s team from Duke Coach Mike Krzyzewski this summer and will be at the helm for the FIBA World Cup in China and the Tokyo Olympics in 2020. That schedule adds up to a couple of long years for any coach, let alone one who turns 70 on Jan. 28.

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