Cristiano Ronaldo scored in the 73rd minute to send Barcelona to its first loss in 55 home games and put Real Madrid on the cusp of breaking the Catalan giants' three-year hold on the Spanish league crown with a 2-1 win Saturday.

Sami Khedira opened the scoring in the 17th minute with Madrid's league-record 108th goal of the season. Ronaldo sealed the victory with his league-record 42nd goal moments after Alexis Sanchez tied it for Barcelona.

Madrid's 19th league game without a loss lifted it seven points ahead of Barcelona at the top of the standings with four rounds to go.

"This was a crucial step forward, now we have to finish it off," Madrid midfielder Xabi Alonso said. "We barely suffered. We controlled the game to perfection."

After managing only a single win in nine previous games against Barcelona since joining Madrid, coach Jose Mourinho finally guided his team to a long-coveted victory in this stadium.

This was Madrid's first victory at Camp Nou since 2007 and Mourinho's first career win in the stadium in 10 visits with three different teams. Barcelona's previous home defeat was 2-0 to Hercules on Sept. 11, 2010.

The game had been hyped as a duel between Barcelona's Lionel Messi and Madrid's Ronaldo, but this time the Portugal forward came out on top and moved one goal ahead of his Argentine rival in their duel to see who is the top all-time scorer in a single Spanish league season. Messi's usual incursions through the middle were bottled up by Madrid's disciplined defense.

"Those of us who work with (Ronaldo) every day are not surprised at him coming through in the key moments," said Madrid assistant coach Aitor Karanka, who spoke in place of Mourinho. "For me, he is the best player in the world."

With the score suddenly even and the crowd roaring, Ronaldo showed again that Madrid is one of the best counterattacking clubs in Europe. He used his speed to race free and beat goalkeeper Victor Valdes with little angle from the right flank.

Madrid went ahead in the first half after a pair of defensive errors by Barcelona, and Khedira poked the ball across the line to silence the home crowd. Madrid broke the league record the club had set with 107 goals in the 1989-90 season.