Huddersfield defender Tommy Smith has been airlifted to hospital following an apparent heavy collision with his own team-mate Joe Murphy.
The incident occurred in the 90th minute of Town's 2-1 defeat against Leeds at the John Smith's Stadium.
Smith was beaten to a cross by Leeds striker Billy Sharp, who headed a last-gasp winner for the visitors, before the centre-back seemed to collide with goalkeeper Murphy.
A Yorkshire Ambulance Service NHS Trust spokeswoman said: "We received a call at 14.28 to reports of a medical emergency at Huddersfield.
"Two ambulances were sent and the air ambulance was in attendance.The air ambulance took one patient to Leeds General Infirmary."
Huddersfield manager Chris Powell said in his post-match press conference: "I am shocked after seeing that. I made sure I saw him and his family and hopefully everything will be okay."
A late goal from substitute Billy Sharp ensured Leeds United grabbed all three points from local rivals HuddersfieldRead the full story ›
Massimo Cellino has announced he has resigned as president of Leeds but says he will return in April.
Cellino has been disqualified as an owner and director of the club by the Football League following a tax evasion conviction in Sardinia last year.
That conviction becomes spent in April which will allow the Italian businessman to return.
Cellino said in a statement: "It is with great sadness and frustration that I have to take this step, however I abide by the Football League's decision to temporarily disqualify me from this great football club and will return in April in good health and good spirits.
"I have done my best for a club and fans that I hold close to my heart and it is now financially much stronger than it has been for a long time. It will continue to thrive and I am sincerely looking forward to returning very soon."
A Professional Conduct Committee has rejected an appeal by Massimo Cellino against his disqualification from owning Leeds UnitedRead the full story ›
Massimo Cellino will seek to have his disqualification from owning Leeds United overturned at an appeal hearing on ThursdayRead the full story ›
The Football League have announced that three Championship clubs have been placed under a transfer embargo.
Leeds United, Blackburn Rovers and Nottingham Forest have all suffered the same punishment.
All three clubs will be prevented from signing players in the January transfer window after failing to meet the League's Financial Fair Play rules.
Leeds United caretaker manager Neil Redfearn says he is 'very close' to taking the role on a permanent basis.
Championship side Leeds United has confirmed the sacking of coach Darko Milanic after just 32 days in charge of the club.
The club said Neil Redfearn will take charge of first team training on Monday morning and president Massimo Cellino apologised to the fans for the team's recent poor results.
BREAKING: Club president Massimo Cellino says: "I want to apologise to the supporters, they deserve better results." #lufc
Milanic was appointed on 23 September but did not win any of his six games in charge.
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Police have begun an investigation at Leeds United after spy cameras were apparently found at the Elland Road stadium, in a security sweep ordered by new boss Massimo Cellino.
Detective Superintendent Pat Twiggs, head of crime for Leeds, said: "We can confirm that police are investigating an allegation of theft relating to Leeds United Football Club following a report made by the club made on April 9".
West Yorkshire Police would not confirm details of their inquiry but according to reports, officers were called to the ground on Wednesday after surveillance equipment was found in the boardroom and toilets.
Italian businessman Massimo Cellino has been disqualified from buying a majority stake in Leeds under the Football League's 'owners and directors' test', the League has announced.
Mr Cellino was recently found guilty in Italy of non-payment of import duties on a boat, resulting in a fine of €600,000 (£500,000).
The Football League said its board had "agreed unanimously that the decision of the Italian Court does constitute a disqualifying condition" under its Owners' and Directors' Test.
Mr Cellino is entitled to appeal within 14 days.