- Éder Militão (26' OG)
Visiting manager Xavi Hernandez called Madrid favourites ahead of the tie and, despite the Catalans having won the Spanish Super Cup Clasico 3-1 in Saudi Arabia on Jan. 15, the LaLiga leaders came into the match without the injured Pedri, Ousmane Dembele and Robert Lewandowski.
- Kirkland: Barca win over Madrid keeps double hopes alive
- Marsden: When Barca, Madrid played 4 times in 18 days
Even without three of their top attacking players, Barca went in front before the half-hour when Ferran Torres picked off a poorly played back pass by Madrid and played in Franck Kessie, who had his attempt blocked by Thibaut Courtois only for Eder Militao to redirect the rebound into his own net.
The fiesty first half ended with Barca 1-0 up and Vinicius Junior on a yellow card after a midfield tussle saw the Brazil international take Frenkie de Jong down in a headlock after a physical battle for the ball between the two.
Kessie nearly made it 2-0 for Barca in the 72nd minute, but his shot from close range from another Torres pass was inexpicably blocked off target by second-half substitute Ansu Fati.
It was also the first match between the rivals since it became public that Barcelona paid millions of euros over several years to the vice president of the country's refereeing committee.
A banner by Madrid fans at the Bernabeu said: "Clean and white, never tarnished". Before the match a small group of fans protested outside the stadium and threw around banknotes printed with Barca president Joan Laporta's face on them.
"I am happy to have played more Clasicos than anyone else," Busquets said. "As a player these are the games you love. I am lucky to have been at the best club in the world for many years and I am still enjoying it.
Barcelona was coming off a 1-0 loss at Almería in the Spanish league, which marked the first time the Catalan club failed to score since October. Before that, they were eliminated by Manchester United in the Europa League playoffs.
"It was an important win, but we still have the second leg to go, so we are not getting ahead of ourselves yet," Busquets said. "We came into the game on the back of two defeats, so this strengthens the group.
"We had players out, but the team competed well, we were solid, got the goal. And even without having control of the ball as we would have liked, we didn't suffer that much."
Madrid were without central defender David Alaba and left-back Ferland Mendy because of injuries. Rodrygo was back from injury but started on the bench, with Vinícius and Karim Benzema in the starting lineup.
The two sides meet again on March 19 in LaLiga, where Barcelona are currently seven points ahead of second-placed Madrid, before the decisive Copa del Rey second leg at the Camp Nou on April 5.
The winner will play either Osasuna or Athletic Bilbao, who were 1-0 victors in the other semifinal on Wednesday, while the final is set for May 6 in Seville.
Barcelona have most Copa titles with 31, eight more than Athletic. Madrid are next with 19, but none since 2014.
"You can see how equal these games are, the two teams compete really well," Busquets said. "We have won the last two (Clasico wins) now and, with the lead from tonight, maybe we have a slight advantage in the tie, but not much."
Courtois felt the hosts had dominated the game, but said regardless of the final score it wouldn't have any affect on what happens in the second leg or the remainder of the LaLiga season.
"We dominated the game," Courtois said. "They were quite defensive. We were unlucky to concede the goal. It was hard for us to get shots on goal, and to create chances. We played a good game, in control, but we didn't find the chance.
"They defended well, they concede few goals. We didn't get the final ball. It won't change or affect the return leg, or the league."
Information from the Associated Press was used in this report.
- José Luis Munuera Montero