Valencia defender Victor Ruiz says his side will go all out to put an end to Radamel Falcao's goalscoring run as they welcome Atletico Madrid to the Mestalla on Saturday.
Ruiz's team have kept just one clean sheet in their opening nine La Liga games as new coach and former Los Che centre-half Mauricio Pellegrino has struggled to implement new defensive ideas.
Meanwhile, Falcao has scored in each of his last 11 matches for club and country, and already has 17 goals this season.
Ruiz, 23, says he and his team-mates have to attempt to stay close to the elusive striker this weekend. "You must be doubly concentrated, always, against Falcao," he explained.
"It might seem he is not there, but he is the best finisher in the world. We must help each other to mark him.
"Maybe he does not stand out for his pace. But he scores goals. In front of goal, he is the number one."
Falcao scored twice against Valencia in last season's Europa League semi-final, one a close range header, the other a long distance strike, and a goal at the Mestalla this weekend would bring him to 50 for Atletico in little over 12 months.
Ruiz's team-mate Aly Cissokho stressed that Atletico, who have won their last 13 games in all competitions, had more attacking threats than just the Colombian.
"The most important thing is to be very concentrated and well positioned together," left-back Cissokho said.