Update 9:01 p.m.: The Spurs released a statement confirming the decision.
San Antonio's Tim Duncan has decided to opt into the final year of his contract at $10.3M, league sources tell Yahoo Sports.— Adrian Wojnarowski (@WojYahooNBA) June 23, 2014
There had been rumors Monday that Duncan was considering opting out and signing for less money to give the team more flexibility, but Duncan evidently decided against that.
The real question for this is whether it means Duncan is closer to retiring after finishing this contract and rejecting a longer-term deal, or if he's simply putting off the decision until next summer. After talking about the end of his career coming sooner than later, the Spurs' fifth title obviously makes it hard for him to walk away. So Duncan will come back for another year and then decide next year how much longer, if at all, he wants to keep battling. If the Spurs were to repeat, you can bet he would want to come back. If the Spurs were to struggle, he could decide he has had enough of the fight.
But for now, the question has been put off. The Big Fundamental returns for another year.