Ten-man Osasuna spoiled caretaker coach Juan Ramon Lopez Caro's first home game in charge by holding Real Madrid to a 1-1 draw in the Primera Liga on Sunday.
Osasuna had midfielder Francisco Punal sent off after 15 minutes but Real struggled to make the extra man count in a bruising encounter of little quality.
It could have been even worse for Real after Serbia & Montenegro striker Savo Milosevic headed the Navarrans in front in the 76th minute.
Second-half substitute Roberto Soldado rescued a point for Real six minutes from time.
Real were jeered off the pitch once again.
Striker Ronaldo told Canal Plus television: "Playing for so long with an extra man it is clear we should have won.
"They pressured us a lot but it was our errors that were the problem. There is still a lot of time left for us in this league to get back to playing good football."
Osasuna stay second on 35 points, two behind leaders Barcelona, who beat Cadiz 3-1 on Saturday.
Real are third on 29 points, the same as Villarreal, who came from behind to beat Getafe 2-1 thanks to a sublime free kick from Argentina playmaker Juan Roman Riquelme and a well-worked winner from Uruguay striker Diego Forlan.
Deportivo Coruna, in fifth, and Valencia, in sixth, also have 29 points.
The team from Coruna beat Celta Vigo 3-0 on Saturday while Valencia won 1-0 at Alaves on Sunday courtesy of Raul Albiol's early strike.
Sevilla fought back from 2-0 down to beat nine-man Real Sociedad 3-2, with all their goals coming in the last 14 minutes.
Sociedad took command through Mikel Labaka and Gaizka Garitano before a double by striker Kepa and one from Frederic Kanoute completed a dramatic recovery by Seville, who are seventh on 26 points.
EARLY DISMISSAL
Five players were sent off in Racing Santander's 1-1 draw at home to Malaga. Referee Carlos Megia Davila sent off one player in each half for Malaga, and three for Racing after the break.
Osasuna made it clear they were not about to be pushed about in the Bernabeu with several robust challenges early on.
Punal's arm caught Real defender Roberto Carlos in the face and the Brazilian's overreaction contributed to the Osasuna player's dismissal.
The visitors worked hard to deny Real space and put on a tactically astute display.
Real did not carve a clear chance until the 55th minute when Ronaldo's weak shot was cleared off the line by Carlos Cuellar.
Osasuna looked to have sneaked a winner when a long free kick from Josetxo eventually found Milosevic, who steered his header past Iker Casillas from close range.
Guti, though, picked out Zinedine Zidane's run into the area and the Frenchman hooked the ball across goal for Soldado to equalise after 84 minutes.
Visiting keeper Ricardo then denied Guti and Ivan Helguera in a frantic final few minutes.
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