Real were held to a 1-1 draw away to Athletic at the San Mames Stadium, leaving Barcelona with the only 100% record remaining in La Liga.
Manager Julen Lopetegui remained positive after the match, but admitted his team should have been more clinical in the game, the Spaniard stating: "We weren't decisive in the big moments.
"It's a difficult ground, but I think that in the second half the boys were much more successful in an attacking sense and we generated many chances."
Lopetegui's decision to bring on Isco for Luka Modric, after the Croatian had not been able to influence the game from midfield as he so often does, proved pivotal after the Spaniard scored Real's equaliser.
Lopetegui made it clear in his press conference why he brought on Isco for Modric, explaining: "With Isco we were looking for a player to get behind the midfielders and who could receive the ball."
Lopetegui then chose to bring on Lucas Vazquez late on instead of newly-named number 7 Mariano as Real pushed for the winner, with Real's manager explaining: "He (Mariano) could have been an option.
"But we understood that Gareth Bale needed a rest and we decided to put Lucas on to create a lot of danger."
Lopetegui ended his press conference acknowledging his side should have been able to win the game as they pushed for a winner late in the second half, the Real manager saying: "In the second half we have improved a lot and in a very intense match, we were superior and could've scored more than one goal."