The former Villarreal striker feels that Betis coach Victor Fernandez will soon start looking for other attacking options if he does not hit the back of the net in the derby against Sevilla.
"Another game has gone by and I still haven't done my job and scored a goal," the Argentinian said.
"I get desperate when I see the coach substitute me 15 minutes before the end of the match.
"The opportunities to score are rare and a number of games have already gone by."
The striker also inferred that Betis' style does not suit him, as they are used to playing without a target man.
"Before, we played without a target man, who preferred ball to feet. They play differently to me as I prefer the ball in the air.
"I don't get the chances," he added. "If I miss opportunities I am the first to criticise myself.
"I look at the reports featuring Deportivo or Real Sociedad, teams that cross the ball into the area, and I think that I could have taken those chances."
