PHOENIX -- Kevin Durant headed to the locker room just before halftime of Tuesday's 104-93 win in their NBA Cup matchup against the San Antonio Spurs with a left ankle sprain and was later ruled out.  The Suns didn't have an update on Durant's status after the game. Phoenix coach Mike Budenholzer said Durant's ankle stiffened up on him at halftime.  Sprinting the floor in transition, Durant drove to the basket and attempted to cut between Spurs defenders Julian Champagnie and Devin Vassell. Durant stepped on Champagnie's left foot as he rose to take the shot. Durant fell to the floor, landing flat on his back before immediately grabbing at his left ankle. Teammate  Ryan Dunn helped Durant back to his feet, as officials had whistled Champagnie for a foul on the play with 4:30 remaining before intermission.   Durant remained on the floor to connect on both free throws. Durant also knocked down a 14-foot jumper 22 seconds later,...