Valencia surrendered their 100 percent record at Mestalla and slipped to third in the Primera Division table after being held to a 0-0 draw by Athletic Bilbao.
Nuno Espirito Santo's men were starved of goalscoring chances by Ernesto Valverde's organised side and are now three points behind leaders Real Madrid and a point from Barcelona.
Valencia had scored three times in each of their five matches at Mestalla but were pegged back by a determined and energetic Athletic side, who came into the game on the back of two consecutive league wins but hurting from their untimely exit from the Champions League in midweek.
The Basques were without the injured trio of Markel Susaeta, Iker Muniain and top scorer Aritz Aduriz, so Guillermo Fernandez started up front on his own, but the youngster struggled to influence proceedings and had to face the ignominy of being substituted after just 38 minutes, replaced by Benat.
Athletic had few chances to show for their positive start to the first half, their only notable effort on goal being a wayward header from Oscar de Marcos.
Valencia slowly grew into the game as the break approached, with Rodrigo Moreno dragging a low shot a few feet wide of the near post, Paco Alcacer heading over the bar and Pablo Piatti shooting straight at the feet of Athletic goalkeeper Gorka Iraizoz.
Both sides continued to struggle to find openings in the second period and they were not helped by a shoddy Mestalla pitch.
Valencia brought on big-name signing Alvaro Negredo with 21 minutes to go but the former Manchester City striker could not add the firepower necessary in attack to break the deadlock.
It was Athletic who created the best chance of the second half. De Marcos lobbed a free-kick towards the far post and defender Xabier Etxeita lashed at it from only a few yards out but his shot bounced off the face of Valencia stopper Diego Alves and was eventually cleared.
Although Athletic were frustrated at passing up such a great opportunity to take all three points, they should be encouraged at becoming the first team to hold Valencia at Mestalla and they remain unbeaten in their last three league outings.