Kevin Durant (31 points, 14 rebounds, seven turnovers) goes scoreless in overtime as the Thunder drop their first home game of the Western Conference finals in Game 6. (Tom Pennington/Getty Images)

A wacky series in which every game was a lopsided affair and neither the Oklahoma City Thunder nor San Antonio Spurs could win on the road finally went in the opposite direction on Saturday night at Chesapeake Energy Arena. After five forgettable finishes, Game 6 of the Western Conference Finals lived up to expectations with two of the league’s best teams seeking a berth in the NBA Finals.

The calm, measured approach of Tim Duncan and the Spurs won out over the frantic, furious style of the Thunder in a 112-107 overtime victory that earned San Antonio a rematch with the Miami Heat for the NBA championship.

“We weren’t relying on a seventh game,” Duncan said. “We wanted to finish it here. So we were playing with as much pressure as they were. There were ups and downs and back and forths. I don’t think anybody was playing with that much pressure on their shoulders, but [we] found enough plays to win down the stretch.”

Undaunted by the commotion around him, Duncan — as he has done before, in many challenging settings — took control of the extra frame, scoring seven of his 19 points in overtime as the Spurs reached the Finals for the sixth time in his distinguished career and in back-to-back seasons for the first time. Now, the Spurs will have a chance to exorcise demons of last season, when they were seconds away from claiming the franchise’s fifth NBA championship before they were undone by Ray Allen’s three-pointer in Game 6 and LeBron James’s heroics in Game 7.

“I think our guys, they actually grew from the loss last year,” Spurs Coach Gregg Popovich said. “I call it fortitude. If I can compliment my own team humbly, to have that tough loss, especially the Game 6, and not have a pity party, and come back this year and get back to the same position. I think that’s fortitude.”

Kevin Durant scored 31 points but went scoreless in the extra period, missing his only two shot attempts, including a late three-point attempt to tie the game. He became the eighth most valuable player in the past 11 years to fail the reach the NBA Finals in the season that he won the award.

Kobe Bryant and James are the only MVPs to reach the Finals over that span, but James is the only one to also win a championship, which he has done the past two seasons. As he prepared to walk off the floor in the closing seconds, Durant spoke to Popovich and told him congratulations.

“We fought as hard as we could all night,” Durant said. “We left it all out there. They made plays down the stretch but we didn’t.”

The Thunder rallied from a 12-point second-half deficit, with Russell Westbrook scoring a game-high 34 points. But with Oklahoma City trailing by just one in overtime, forward Serge Ibaka blocked Manu Ginobili on a layup attempt, leading to a three-on-two fastbreak with Westbrook on one wing and Durant on the other. Reggie Jackson (21 points) dropped off the ball to Westbrook and Spurs forward Kawhi Leonard blocked Westbrook’s layup attempt.

Duncan then backed down Jackson and hit a falling bank shot with 19.4 seconds remaining. He glanced at the scoreboard, realizing that the Spurs were about to advance despite playing the entire second half without Tony Parker, who sat with soreness in his left ankle.

“I really don’t know how he does it,” Manu Ginobili said of Duncan. “He’s always got to be ready with a solution down the stretch. We were pretty tired in overtime. They were very physical, and it’s always hard to score against them, and we just started to give him the ball, and he gave us solutions. As always, outstanding.”

The Thunder had faced elimination twice already this postseason, trailing Memphis 3-2 in a first-round series before Durant responded with two of his best games of the playoffs, scoring a combined 69 points with 18 rebounds in the next two games as Oklahoma City rallied to advance. Durant expected to have a more difficult time seeking a huge scoring game against a Spurs team that rarely let’s one man beat it.

Danny Green (11 points) hit a three-pointer from the left corner to put the Spurs up 91-82, but Derek Fisher — the only Thunder reserve to score in the game — answered with a three-pointer as Oklahoma City went on a 9-2 run to get within 93-91 after Durant made a layup. Popovich immediately called a timeout and put Duncan back in the game.

Then the Thunder went on a Westbrook roller coaster-ride that included two turnovers that helped the Spurs push the lead back up to six and two electrifying baskets to give Oklahoma City hope once more.

Durant gave the Thunder its first lead since early in the third period when he drove left around Boris Diaw and made a whirling, underhand scoop shot over Duncan. But Manu Ginobili silenced the crowd on the next possession when he knocked a three-pointer to put the Spurs up 100-99 with 27.1 seconds remaining.

Oklahoma City worked the ball to Durant again but he slipped while driving left around Leonard, lost his dribble and landed on the ball before it rolled to Leonard. Ginobili got fouled but would only hit one of two free throws and Westbrook made two free throws to tie the game.

With a chance to send win the game in regulation, Ginobili missed a fading jumper and buried his face into his fists. Duncan made sure that the agony wouldn’t last.

Diaw, a player who just two years ago was waived from the team with the worst winning percentage in NBA history, was the best player on the Spurs for long stretches as he punished the Thunder for leaving him open and hit three three-pointers. Diaw was also effective in the low post as both a scorer and a passer. He scored 26 points as the Spurs bench outscored the Thunder reserves, 51-5.

The Spurs have been grooming Leonard to be the future of the franchise for some time, but he had been relatively quiet offensively throughout this series while focusing on slowing down both Durant and Westbrook. Leonard scored a series high 17 points with 11 rebounds.

“There’s only one team that stands every year,” Thunder Coach Scott Brooks said. “We’ve worked every day since July to be in this position, to climb to the top, and we came up six games short. We have to keep our heads up and move on.”