The San Antonio Spurs had a comfortable 21-point lead over the Golden State Warriors in Game 1 of the Western Conference finals, but then Kawhi Leonard’s left foot landed on Warriors center Zaza Pachulia’s foot in the third quarter, and it all fell apart.

Before Leonard limped off the court, the Warriors had a win probability of 2.6 percent, but an 18-0 run helped Golden State defeat the Spurs 113-111, allowing the Warriors to overcome the third-largest halftime deficit in a playoff win in NBA history.

San Antonio withstood the loss of Leonard during the series against the Houston Rockets, winning Game 5 in overtime and Game 6 without the two-time defensive player of the year. But defeating the NBA-best Warriors is going to be an entirely different, and considerably harder, challenge.

The Rockets concentrate much of their offense around guard MVP candidate James Harden. He used more than a third of the team’s possessions during the regular season (34.2 percent) and the playoffs (35.3 percent) and was responsible for better than 80 percent of the team’s offense (shots and assists) when he was on the court in the series against San Antonio, producing a team-high game score of 18.2. Only two other players for Houston were in double digits: Clint Capela (14.2) and Trevor Ariza (12.3). So when the Spurs held Harden to one of the worst games of his career — 10 points on 2-of-11 shooting in more than 36 minutes — they won easily.

The Warriors, meanwhile, have two former MVP winners, Stephen Curry and Kevin Durant, along with all-stars Klay Thompson, Draymond Green and Andre Iguodala. Only one of those players, Curry, uses more than 30 percent of the team’s playoff possessions. Three, Curry, Green and Durant, touch the ball more than 50 times per game, with two, Curry and Green, at 80 or more. Only Harden touched the ball more than 50 times per game for Houston in the postseason.

In Sunday’s win, Curry (40 points) and Durant (34) combined for 74 points, the most by any Warriors teammates in a playoff game since 1987. They both have playoff game scores superior to Harden (22.9 for Curry, 20.4 for Durant) with Green close behind (17.8).

And it is Durant who will benefit the most if Leonard is unable to play.

When those two shared the court on Sunday, the Warriors were shooting an effective field goal percentage of 44.7 percent, leading to San Antonio outscoring Golden State by 29.4 net points per 100 possessions. Once Leonard left the game, the Warriors’ offensive rebound percentage spiked to 75 percent(!) with a 69.7 eFG%, leading to a massive turnaround in Golden State’s net rating (plus-78.1 after Leonard’s exit). Durant’s individual points per 48 minutes spiked from 24.4 to 65.2.

Without Leonard on the court, Durant came alive in the fourth period. He hit a three in transition then scored again driving hard to the rim for an easy dunk. He hit another three off the pick-and-roll, then on another possession hit the brakes on a drive while being guarded by LaMarcus Aldridge, allowed him a midrange pullup.

The Spurs, leading 98-95 with less than six minutes to go, made a defensive adjustment to slow down Durant that included Dejounte Murray helping Danny Green against Durant with Aldridge rotating onto Curry. However, as you can see below, that wasn’t enough.

Before the playoffs, the Spurs, with Leonard, had a 15 percent chance of advancing to the NBA Finals, per FiveThirtyEight’s projections. Now those chances are almost cut in half (9 percent), and only figure to go lower if Leonard is not fully healthy for the series.