Substitute Zlatan Ibrahimovic's superb second-half volley secured the three points for the champions and put Pep Guardiola's team back on top of La Liga.

Barca held onto their lead despite the sending-off of Sergio Busquets with almost half an hour remaining, and Madrid's frustration spilled over as Lassana Diarra also saw red late on.

But Alonso, a big-money summer signing from Liverpool, believes the capital club should have taken something from the game.

"I feel like we could have done better," he told

"We deserved more. We had more chances, especially in the first half. It's a shame.

"It was a neck-and-neck battle from start to finish.

"Perhaps they had more possession, but we had better opportunities. They didn't feel comfortable on the pitch.

"It's a pity we couldn't score first because I am sure the outcome would have been much different.

"We played close together and knew how to move the ball quickly in attack, but all we missed out on was a goal."

Despite seeing his side overtaken at the summit, Alonso knows there is plenty of time to make amends and is already looking ahead to Saturday's visit of Almeria to the Bernabeu.

"It was an important match, but it wasn't decisive," he said.

"There is a long season ahead and each match is another step towards the goal. Now we must focus on Almeria."

Madrid and Spain goalkeeper Iker Casillas agreed with his team-mate's assessment of the match.

"We had many chances," he said. "Cristiano Ronaldo had a bunch in the first half, but we lacked accuracy.

"The final score is unfair. We deserved a draw.

"Barcelona capitalised with a great strike by Ibrahimovic."

Madrid director general Jorge Valdano took heart from his team's progress despite the result.

"It was an intense match and we had control during most of it, but the scoreboard reflects otherwise and it is a little unfair," he said.

"We are pleased with our players' composure but disappointed with the outcome. Matches like this one are good to see just where we stand.

"From our standpoint, we feel like we are making good progress."

Cristiano Ronaldo - returning to the side after injury to take part in his first ever 'Clasico' - missed a fantastic chance to give Manuel Pellegrini's side the lead when he shot straight at Victor Valdes with only the Barca keeper to beat.

The Portugal winger went off with 25 minutes left on the advice of the club doctor.

"Cristiano wasn't in good enough shape to play the entire match," Valdano conceded.

"We didn't know whether to start him or not, but the doctor said he could only play for an hour.

"He was more worried about his lungs than his ankle because he needs to get back into a rhythm that he lost from being out for so long."