Fabrice Muamba is in a "critically ill" condition after being admitted to the heart attack centre at London Chest Hospital, Bolton Wanderers have confirmed with the Barts & Middlesex Trust in a joint statement.
The midfielder collapsed to the ground unchallenged in the 41st minute of the first half of the FA Cup tie against Tottenham at White Hart Lane before paramedics promptly rushed onto the pitch to provide mouth-to-mouth resuscitation and use a defibrillator in attempts to revive him.
As the 23-year-old was stretchered off down the tunnel, referee Howard Webb called both teams off the pitch. The game was later abandoned.
Players surrounding Muamba looked distraught, while Bolton chairman Phil Gartside rushed from the stands to the sidelines.
The statement released by Bolton and the Barts & Middlesex Trust read: “Bolton Wanderers can confirm that Fabrice Muamba has been admitted to the Heart Attack Centre at the London Chest Hospital where he is currently in a critically ill condition in intensive care.
“No further information will be issued at this stage.
“The club has requested the media to respect his family's privacy at this time.”
FA chairman David Bernstein has also sent his best wishes to the midfielder.
He said in a statement on the FA's website: "On behalf of The FA, I would like to send our thoughts and prayers to Fabrice Muamba and his family this evening.
“Fabrice has played 33 times for England Under-21s, captaining Stuart Pearce's side during this time and is a player, and more importantly, a person we care greatly for.
“We are in contact with Bolton Wanderers over Fabrice's condition and are awaiting updates.”
Muamba began his career in the Arsenal youth ranks, making his first-team debut at the age of just 17 in a League Cup clash with Sunderland back in October 2005.
The following season, he headed to Birmingham City for a year-long loan spell, and after initially struggling under then manager Steve Bruce, the midfielder soon began to impress, even landing the club’s Young Player of the Season accolade.
A permanent switch beckoned, and while his second campaign at St Andrew’s may not have been as fruitful, with the club relegated from the Premier League, Muamba was to continue in the top flight as current club Bolton secured his services in a deal worth £5 million.
An England regular at youth level, the Zaire-born player has continued to grow at the Reebok Stadium, signing a new four-year contract in 2010, while he is seen as a key first-team member as the Trotters look to battle against relegation.