Jude Bellingham was sent off and 10-man Real Madrid failed to hold its lead against Osasuna in a 1-1 draw in LaLiga.
Kylian Mbappe put Madrid ahead in the 15th minute on Saturday with his 11th goal in as many league games.
But Madrid were outnumbered following Bellingham’s red card, apparently for protesting, five minutes before halftime.
The referee then awarded Osasuna a penalty after a video review and booked Eduardo Camavinga for stomping the foot of Ante Budimir in the box.
Budimir slotted the 58th-minute equaliser past Thibaut Courtois to unleash celebrations at El Sadar Stadium.
The draw in Pamplona puts Madrid’s league lead in jeopardy. Atletico Madrid is two points behind Madrid before hosting Celta Vigo on Saturday evening.
Barcelona can pull level with its top rival if it beats Rayo Vallecano on Monday.
Madrid coach Carlo Ancelotti was also shown a yellow card early after he complained excessively about what he thought was a handball by an Osasuna player in the host’s area.
The decisions by referee Jose Luis Munuera will likely aggravate Madrid’s sense of grievance regarding the refereeing in LaLiga.
Following its loss at Espanyol, the powerhouse sent a scathing letter to Spain’s football federation to decry what it considered “adulterated” refereeing that favoured other teams.
Osasuna, who in September beat Barcelona 4-2 when the Catalan club was leading the league, moved into seventh place.
