Real Madrid dropped their first points of the season as they were held to a 1-1 draw with Athletic Bilbao on Saturday.
Isco's header off the bench denied Athletic only their second win against Madrid in eight years, but Madrid nonetheless lost ground on Barcelona at the top of La Liga after the Catalans beat Real Sociedad earlier in the day.
Thibaut Courtois kept his place in Los Blancos’ goal, while Dani Ceballos was rewarded with a start in midfield at the expense of Casemiro, having impressed for Spain in their 6-0 thrashing of Croatia.
Athletic, meanwhile, started with defender Yeray Alvarez – a year on from his second battle with testicular cancer – and were coached by Eduardo Berizzo, who also fought off the illness.
Los Leones had only won one of their last 17 meetings with the capital giants, and a pulsating encounter at San Mames saw no less than 25 combined attempts on goal and eight bookings.
They looked on their way to doubling that tally when Iker Muniain scrambled in Oscar de Marcos' cutback from the right, but Madrid didn't relent with their pressure as Luka Modric had a volleyed finish disallowed for offside.
Unai Simon was then on hand to parry away a Marco Asensio strike and get down low to his right to tip Modric's low drive around the post.
It was soon Athletic's turn to push on, and the offside flag saved Madrid from conceding a second goal, when former Atletico midfielder Raul Garcia knocked in a free kick against his old rivals.
The second half began on a bum note for Athletic, who lost their goalscorer to injury, but Unai proceeded to put on a masterclass between the sticks.
The 21-year-old was only making his third senior appearances for the Basques, replacing €80m man Kepa Arrizabalaga, and he immediately made amends for spilling a Gareth Bale free kick with an incredible reaction stop to deny Ramos on the rebound.
Unai could do little about Isco’s glancing header, the midfielder having just come on as a substitute, but he bounced back to keep out Asensio’s one-on-one.
Athletic Bilbao 1-1 Real Madrid
Muniain 32 (AB) Isco 63 (RM)
Athletic Bilbao: Unai Simon; De Marcos, Yeray, Inigo, Yuri; Dani Garcia, Benat (Mikel Rico 81); Susaeta, Raul Garcia, Muniain (Capa 54); Williams (San Jose 76)
Real Madrid: Courtois; Carvajal, Varane, Ramos, Marcelo; Modric (Isco 61), Kroos, Ceballos (Casemiro 46); Bale (Vazquez 75), Benzema, Asensio
Referee: Gonzalez Gonzalez