Riquelme sprained his ankle during Villarreal`s 1-1 draw with Sevilla and was substituted after 26 minutes.
Riquelme is an highly influential midfield playmaker and dead ball specialist as well as being Villarreal`s main penalty taker and scored 15 goals in the Spanish first division last season.
"It`s going to be very difficult for him to recover in time, although we`ll have to see how things progress on a day-by-day basis," said Juan Alborch, Villarreal`s chief of medical services.