Pamplona: Jude Bellingham was sent off and 10-man Real Madrid failed to hold its lead against Osasuna in a 1-1 draw in the Spanish LaLiga.
Kylian Mbappé put Madrid ahead in the 15th minute with his 11th goal in as many league games.
But Madrid was outnumbered after Bellingham's red card apparently for protesting five minutes before halftime, the Spanish MARCA newspaper reported.
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 equalizer past Thibaut Courtois to unleash celebrations at El Sadar Stadium.
The draw in Pamplona puts Madrid's league lead in jeopardy. Later on, Atletico Madrid (second in the table) drew with Celta Vigo. Barcelona can pull level with its top rival if it beats Rayo Vallecano tomorrow (Monday).
Madrid coach Carlo Ancelotti was also shown a yellow card early after he complained excessively for what he thought was a handball by an Osasuna player in the host's area.
The decisions by referee José Luis Munuera will likely aggravate Madrid's sense of grievance regarding the refereeing in the Spanish La Liga. Following its loss at Espanyol, the powerhouse sent a scathing letter to Spain's soccer federation to decry what it considered "adulterated" refereeing that favoured other teams.
Osasuna, which beat Barcelona 4-2 in September when the Catalan club was leading the league, moved into seventh place.