Ernesto Valverde explained Sergio Busquets was a late omission from Barcelona's Clasico line-up against Real Madrid due to a fever.
The Spain international was originally named among Barca's starting XI but was a late withdrawal with Ivan Rakitic taking his place.
Confusion reigned with some reports suggesting Busquets was going to be among the substitutes instead, but head coach Valverde confirmed it was illness that meant he missed the goalless draw at Camp Nou.
"It is true that Busquets was feeling bad, he had a fever, before the game," Valverde told Movistar.
"We thought we could have used him in the second half but not in the end. The coach makes the decision based on what he sees."
There was no lack of endeavour in a match that saw both teams create chances to win all three points, a fact acknowledged by Valverde.
"It was a very disputed match in which there were phases for both teams," he added.
"They squeezed us high and created problems with high balls. That's where we've suffered."
On Madrid's high pressing, Valverde said: "We expected this. In the end they are situations of individual duels that you must solve.
"Sometimes we have achieved it and sometimes not."