Sevilla have called on LaLiga to take action after winger Lucas Ocampos was touched "inappropriately" by a fan during their 2-1 win at Rayo Vallecano, the club said on Tuesday.
The incident occurred 33 minutes into Monday's match when a fan poked Ocampos from behind while he was taking a throw-in. The Argentine notified the referee of the incident straight way before continuing to play.
"We would like to place on record our disgust at the incident," Sevilla said in a statement.
"Lucas Ocampos was subjected to an obscene and completely inappropriate act by a home fan. We hope that the appropriate measures outlined in the regulations will be taken to prevent such behaviour from happening again on a football field, and we have expressed this to LaLiga directly."
Rayo Vallecano said in a statement the incident went against their values as a football club and that they were working to identify the fan.
"This isolated action is solely the individual responsibility of the fan who carried it out," the club added.
"Rayo Vallecano is currently working to identify the fan so that, if he is a season ticket holder of the club, the appropriate disciplinary measures can be taken in accordance with the internal regulations."
Ocampos said he wanted the league to treat the incident "as seriously as it takes racism and these things".
"I kept my calm because I have two daughters, I hope this doesn't happen to them in the future," the 29-year-old told broadcaster Dazn.