Ronald Koeman's first game in charge of Valencia ended in a 2-0 defeat at home to Champions League rivals Rosenborg.
The Dutchman had no arguments with the result and admitted: "Rosenborg defended very well, with many players behind the ball. They hit us on the counterattack and performed that expertly.
"We tried everything we could, I have no criticism with our efforts.
"Now we must target finishing in third-place so we qualify for the UEFA Cup."
Valencia's fans again turned on the players and defender Ivan Helguera added: "At home, we must improve very quickly. We need to help the coach, because he's just arrived. He knows we need to improve a lot.
"The reaction of the fans is expected because we haven't won here for a long time and they're suffering."