OAKLAND, Calif. — When Kawhi Leonard rose for a three-pointer early in the third quarter of Game 1 of the Western Conference finals here at Oracle Arena, a game — and a series — whose outcome seemed so certain a few hours before was suddenly very much up for grabs.

But when he landed, San Antonio’s chances in this series came crashing down as Leonard crumbled to the hardwood.

Leonard’s tender left ankle, the same one he had tweaked a few minutes prior and that kept him out of the end of Game 5 and all of Game 6 of the Western Conference semifinals, bent awkwardly as he landed on the foot of Warriors center Zaza Pachulia, and the Spurs were left with a 23-point lead and 20 minutes on the clock against the Golden State Warriors without their superstar forward.

The final score, a 113-111 Warriors victory, felt irrelevant afterward, as did Golden State’s comeback from a 25-point first half deficit. What was clear to those watching when Leonard went down was plain: The Spurs had their chance, and Leonard’s ill-timed landing let it slip away.

“We played an outstanding game for half and a little bit,” Spurs guard Manu Ginobili said. “Then they came back. They overplayed us, they were more aggressive. They made more shots.

“[And], if it wasn’t bad enough, we lost our best player that was struggling already with a bad ankle. So it’s hard to see the positives, even though we were 20-something up. A very bad outcome of the game.”

A very bad outcome, indeed.

The Spurs spent that “half and a little bit” teaching the Warriors how the game should be played. In many ways, it felt like a continuation of the last time these two teams met here: a 129-100 beatdown San Antonio handed Golden State in the season opener. The Spurs were getting brilliant play from LaMarcus Aldridge in the post and Leonard on the perimeter while watching the Warriors systematically fall apart as they failed to make routine plays.

Then Leonard landed on Pachulia’s foot, and everything changed. The play engendered plenty of controversy, with the Spurs — a franchise that has retired the number of Bruce Bowen, who became synonymous enough with sticking his feet under jump shooters that the rule put in place to prevent it is nicknamed after him — frustrated by the loss of their star, and with plenty of debate around social media (not to mention the league itself) that Pachulia may have intentionally gotten his foot in the vicinity of Leonard’s.

For their parts, Leonard dismissed that idea postgame, though he admitted he’ll “have to see the play.” Pachulia, meanwhile, didn’t mince his words when the possibility was brought up to him.

“That’s really stupid,” he said. “I’m not that good to do intentional stuff like that … I hate anybody going down with an injury. I’m an athlete, too, so I wish it’s nothing serious for him.”

Regardless of intent, from the moment the Spurs lost their star, they seemed to be running uphill in an avalanche. In what felt like the blink of an eye — but in reality was 3:36 of the game clock — the Warriors fired off 18 unanswered points as the home crowd spurred them on for more.

It took another 12 minutes for the Warriors to finally take the lead for good, and the momentum the Spurs had built with their crisp play through those opening 28 minutes before Leonard limped to the locker room was gone. In its place was a team that looked understandably rattled without him.

“Good observation,” Spurs Coach Gregg Popovich said with a heaping dose of sarcasm afterward of his team’s disintegration without Leonard. “You’re correct. We’ve got to move around it. Our defense got a little [stuck in the] mud.

“[We] couldn’t get anybody to score, and they’re fairly talented, as it showed.”

Right up until Leonard’s injury, what had felt to virtually everyone involved like a rote series seemed to be anything but. San Antonio had arrived here Sunday morning for the start of this best-of-seven with nothing to lose, and played like it. Popovich spent his pregame news conference smiling and cracking jokes, acting like a man who knew his team entered this series, despite the immense success the Spurs have enjoyed over the past two decades, in the incredible rare position of having absolutely no one outside of those employed by San Antonio thinking his team had any chance of winning this series.

It’s hard to imagine a positive outcome for San Antonio after the way Sunday played out. If the Spurs had managed to hang on and win without Leonard, they could have gone home for Game 3 on Saturday night and hoped that their star might be healthy by then. Instead, they’re now down in the series, and while Leonard said all the right things after the game — “I feel good,” Leonard said. “I’ll get back healthy” — the chances of him returning for Game 2 seem exceedingly remote regardless of what the results are from the MRI exam he’s expected to receive on his injured ankle.

And while the Spurs annihilated the Rockets in Houston to close out the Western Conference semifinals without him, trying to win even one game against this Golden State team with him in street clothes seems all but impossible.

“I have faith in my teammates,” Leonard said, “and we’re going to see what happens in Game 2.”

What happens in Game 2, and the rest of this series, almost feels as if it doesn’t matter. This was San Antonio’s chance to stun Golden State, to hit the favorites in the mouth and turn what was expected to be a quick and painless victory for the Warriors into the kind of battle everyone hoped for.

Then Leonard came down on Pachulia’s foot. And as he hobbled off the court, San Antonio’s chances of winning this series — and, as it turned out, this game — went with him.