The Golden State Warriors took a 3-1 series lead over the Houston Rockets on Sunday, but it might ultimately be the game that prevents the defending champs from repeating. Stephen Curry suffered a knee injury at the end of the first half, giving the Warriors an uphill battle on their road to the NBA Finals.

After Curry made his way to the court during halftime and realized he was unable to play, he returned to the locker room and was ruled out with what the team called a “sprained right knee.” The point guard will undergo an MRI on Monday, and there is speculation that this injury is more serious than the ankle injury that forced him to miss Game 2 and Game 3 of the first-round series. A person with knowledge of the situation told USA Today’s Sam Amick the fear is that Curry sprained his MCL.

If that early prognostication proves to be true, the Warriors will have to get used to the idea of playing without Curry. The recovery time for MCL sprains are different, but it stands to reason that the 28-year-old would miss a significant amount of time.

Assuming the Warriors eliminate the Rockets, which they are favored to do in Game 5, their second-round series will begin sometime between April 30 and May 3. The Western Conference Finals would start approximately two weeks later, and the NBA Finals are scheduled to begin on June 2. Curry might only miss a few games, and head coach Steve Kerrs seems to be preparing for the worst.

“Feel bad for Steph, but we gotta move on,” Kerr said on Sunday.

With a healthy Curry, the Warriors were odds-on favorites to win a second straight title. Curry had one of the greatest seasons in NBA history as Golden State won a record 73 regular-season games. Defending the title without Curry could be an insurmountable challenge.

Leading the league with 30.1 points per game, last year’s MVP shot 50.4 percent from the field, 45.4 percent from three-point range and 90.8 percent from the free throw line. Curry set a record with 402 three-pointers made after no player had ever even reached 300 in a season, and his PER of 31.46 ranks eighth in NBA history.

In the regular season, the Warriors outscored opponents by 17.9 points per 100 possessions when Curry was on the court. Without their star player, Golden State was outscored by 4.3 points per 100 possessions. In the playoffs, the Warriors are better by 17.5 points per 100 possessions with Curry than without him.

Golden State did manage to rally around their injured leader in Game 4, outscoring Houston by 27 points in the second half. Draymond Green and Klay Thompson took over by finishing a combined 11-of-17 from three-point range.

Curry is only a part of what makes the Warriors great. Green was the runner-up for Defensive Player of the Year, and he could finish in the top 10 in MVP voting. Even playing alongside the NBA’s top scorer, Thompson managed to finish 12th in the league with 22.1 points per game, and his above-average defense makes him a top-20 player in the league. Andre Iguodala was the runner-up for Sixth Man of the Year, and the Warriors are the NBA’s fourth-best defensive team.

But asking the Curry-less Warriors to reach the NBA Finals, let alone the Western Conference Finals, would be a lot to ask. The West features four of the NBA’s top five teams, and Golden State could have a hard time beating the Los Angeles Clippers in the next round. L.A. outscored Golden State in three games this season when Curry was on the bench.

The San Antonio Spurs won 67 games in the regular season, and they’d become the favorites to win the title if Curry is ruled out for multiple weeks. Curry was essential in helping the Warriors beat the Spurs twice in April to secure the No.1 seed in the West. Golden State outscored San Antonio by 21 points with Curry on the court, but the Spurs outscored the Warriors in both games when Curry was on the bench. The Warriors had a hard enough time scoring against the league’s No.1 defense. Two of their three lowest offensive outputs came in games against San Antonio.

If the Warriors find themselves in a matchup with the Oklahoma City Thunder, a trip to the finals is far from guaranteed. Oklahoma City failed to beat the Warriors this season, but they have one of the best duos in the league. The combination of Kevin Durant and Russell Westbrook might be too much for Golden State to overcome if they don’t have Curry.

The Warriors finished with a 3-2 record in games without Curry, beating Houston twice and the Atlanta Hawks once. They lost Game 3 to the Rockets in the final seconds, and the Dallas Mavericks blew out Golden State by 23 points on Dec. 30.