Aston Villa captain Stiliyan Petrov has been diagnosed with acute leukemia, the club said on Friday.
His named started trending on Twitter instantly after the announcement.
"The Villa Board received news today that our long-standing captain Stiliyan Petrov has been diagnosed with Acute Leukaemia," his club said in a statement.
The club's statement continued: "Stiliyan developed a fever following the Arsenal game last Saturday and subsequently underwent tests conducted by Dr Ian McGuinness.
"Haematology experts confirmed the diagnosis today. We expect to learn more about Stiliyan's situation in due course and we have moved quickly to support him and his family.
"During this time we ask that Stiliyan's privacy is placed ahead of all inquiries and trust that we will share information as we receive it.
"Stiliyan is cherished by many and he will get from Villa every ounce of love and support that we have to help bring this to a positive conclusion."
Messages of support have flooded in for the former Celtic player:
Celtic's website published a statement from manager Neil Lennon which said: "We are all absolutely devastated to hear this news.
"Knowing Stiliyan as I do, and the many obstacles he has overcome in his life to get to the peak of his career, he will overcome this one too."