Aston Villa have pledged "every ounce of love and respect we have" to captain Stiliyan Petrov after he was diagnosed with acute leukaemia.
The condition was diagnosed following tests after the Bulgaria international, 32, developed a fever following last Saturday’s defeat to Arsenal.
A statement from the club said: “The Villa board received news today that our long-standing captain Stiliyan Petrov has been diagnosed with acute leukaemia.
“Stiliyan developed a fever following the Arsenal game last Saturday and subsequently underwent tests conducted by Dr Ian McGuinness.
“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.”
STILIYAN PETROV FACTFILE
1979: Born July 5, Bulgaria.
1995: Begins career with father Aliosha's former club, Montana.
1996: Joins CSKA Sofia but does not make first-team debut until 1998.
1999: March - Makes debut for Bulgaria in a friendly draw with Belgium.
July - Signed by then Celtic head coach John Barnes from CSKA Sofia for £2million at the age of 19.
2000: March - Scores first goal for Celtic in a 6-2 win over Dundee at Parkhead before winning first trophy as Hoops clinch CIS Insurance Cup with 2-0 win over Aberdeen at Hampden Park.
2001: January - Captains Bulgaria national team for the first time in friendly win over Mexico.
March - After helping Celtic towards a domestic treble, breaks his leg in Bank of Scotland Premier League win at St Johnstone.
May - Voted Young Player of the Year in Scotland.
June - Wedding to Paulina is broadcast live on Bulgarian television.
2002: April - Celtic clinch second successive SPL title with 5-1 win over Livingston.
May - Plays in UEFA Cup final as Hoops are defeated by Jose Mourinho's Porto in extra-time. Celtic lose the SPL title on the final day of the season to Rangers on goal difference.
Voted Bulgarian Player of the Year.
2004: April - Scores winning goal at Kilmarnock as Hoops regain title.
June - Sent off while playing for Bulgaria in the European Championship finals against Sweden.
2005: May - Wins Tennent's Scottish Cup with Celtic after defeat of Dundee United at Hampden.
October - Scores first hat-trick in 5-0 win over Motherwell in the SPL.
2006: January - Signs contract extension with Celtic until 2009.
May - After helping Celtic clinch the SPL title, hands in an official transfer request, which is rejected by the club.
August - Joins Aston Villa on a four-year contract in a £6.5million transfer, rising to £8million.
October 12 - Announces decision to retire from international football for as long as Hristo Stoichkov remained Bulgaria coach, although he would make himself available again the following March after mending bridges with Stoichkov.
December 11 - Scores his first Villa goal in a 2-2 draw against Sheffield United as he struggled for form early in his Premier League career.
2008: April 12 - Scores a famous volley from the half-way line against Derby, but it was his first goal of the season.
October 2 - A rejuvenated Petrov takes the captain's armband for the first time as a Villa player for a UEFA Cup game against Litex Lovech.
2009: May 20 - Signs a new four-year deal with Villa after being named both supporters' and players' Player of the Year.
August - Emerged as Gareth Barry's permanent successor as club captain.
2010: January - Regained the Bulgaria captaincy, lost during his dispute with Stoichkov, following the retirement from international football of Dimitar Berbatov.
2011: March 26 - Won his 100th cap for Bulgaria in the 0-0 draw with Switzerland in a Euro 2012 qualifier.
2012: March 30 - Diagnosed with acute leukaemia.