Tim Duncan has June 24 deadline

San Antonio Spurs star Tim Duncan has until June 24 to notify the team whether he intends to pick up his $10.3 million player option for next season, according to sources familiar with the terms of the contract.

Such opt-in or opt-out dates for most players are typically June 30, right on the eve of free agency, but sources told ESPN.com the contract is set up to provide the Spurs with a fairly firm read on the 38-year-old stalwart's plans for next season before offseason business starts July 1.

The date still can be moved closer to July 1, sources said, if both parties agree to do so, but it obviously behooves San Antonio to have an answer as early as possible so it can properly chart its course not only in free agency but for the June 26 draft.

The Spurs hold a commanding 3-1 lead over the Miami Heat in the NBA Finals after winning both games in Miami this week in convincing fashion. No team in Finals history has ever recovered from a 3-1 series deficit.

Amid rising speculation that Duncan and Spurs coach Gregg Popovich might ultimately be moved to walk away together in the event that the team goes on to win its fifth overall championship, San Antonio's two faces of the franchise have routinely deflected any questions about their future plans.

But sources say the Spurs, to this point, are quietly operating under the assumption that Duncan and Popovich will indeed be back next season. Both of their current contracts, along with those of fellow Spurs pillars Tony Parker and Manu Ginobili, expire after the 2014-15 season, provided Duncan decides to opt in.

"I don't know when I'm going to retire," Duncan said at a news conference before Game 1 of the Finals. "I don't know what the factors are going to be. I don't know any of that and I don't care about any of that stuff right now. It will happen when it happens."

All three of Popovich's mainstays are playing for what has to be considered major bargains given their stature and ongoing production. Parker, at 32, is earning $12.5 million this season. Ginobili, at 37, makes $7 million.

Ginobili told the San Antonio Express-News before the Finals that he will "for sure" be back next season, which has only added weight to the notion that the hyper-competitive Duncan would play on for at least one more season even if San Antonio wins it all and avenges its devastating seven-game defeat to the Heat in the 2013 Finals.

Duncan averaged a mere 29.2 minutes this season as part of Popovich's long-running efforts to keep the regular-season workload down for each of his three veterans and has played strong throughout the playoffs.

However, one more victory over the Heat would give Duncan and Popovich an opportunity to walk away from the game as champions, just as fellow Spurs icon David Robinson did in 2003 after helping San Antonio to a six-game Finals victory over the New Jersey Nets.

Duncan's former teammate and close friend Malik Rose, now a broadcaster for the Philadelphia 76ers and Sirius Radio, told ESPN.com last month that he knows "for a fact" that Duncan is "not ready for it all to end."

But Rose says he is rooting for Duncan and Popovich to leave the game together -- whenever the time comes.

"I would bet money Pop and Tim leave together," Rose said, "and it's gonna be really, really cool."

"All I know is they're irreplaceable," said Spurs lifer Elliott, now San Antonio's color broadcaster and a close friend of Duncan's to this day. "You can't replace 'em. It's gonna be an entirely new era here in San Antonio (when they're gone).

"I tell people all the time that we're spoiled. We don't have the real NBA here. We've had two superstars in Timmy and David who didn't read the superstar handbook."