(CNN) -- Mexican crooner Vicente Fernandez, an icon of folk music known for his ranchera ballads, will undergo a liver biopsy in Houston on Tuesday, he announced.
Considered Mexico's most famous living singer, Fernandez told CNN affiliate Foro TV that doctors had found a 2-centimeter "ball" in his liver that requires examination.
"They don't know what it is, but it shouldn't be there," Fernandez said.
Fans will anxiously await the results of the biopsy. Fernandez asked the public not to be alarmed and to pray for him.
"To clarify things, in reality I don't have anything, unless they tell me something" after the test, he said.
Near Mexico City's Plaza Garibaldi, where mariachi groups often perform Fernadez's songs, fan Isidro Salazar said he was praying for the singer.
"I hope that God gives him relief," Salazar said.
Many in Mexico count Fernadez's songs among their personal repertoire and can sing lines from his well known ballads on cue.
Fernandez's career has spanned four decades, and he is known as the king of ranchera music.
He has appeared in more than 25 films as well, though his music career has eclipsed his acting career.
"For more than 45 years, Vicente Fernandez has maintained his position as the biggest living singer in Mexico, combining a operatic vocal range with a deep comprehension of the folk roots of ranchera music," his official biography says.
The 72-year-old has won a bevy of awards, including, this month, three Mexican Music Billboard awards. He has a star on the Hollywood Walk of Fame.
CNN en Español's Krupskaia Alis contributed to this report.