Luton Town captain is "stable and undergoing further tests" after suffering a cardiac arrest in the Premier League clash at Bournemouth on Saturday, which was abandoned with the scores at 1-1.
Lockyer collapsed in the second half of the game at the Vitality Stadium and had to be stretchered off after receiving medical attention.
The 29-year-old was applauded by both sets of fans and was responsive as he left the pitch.
Luton later said Lockyer was "stable and currently undergoing further tests".
"Our medical staff have confirmed that the Hatters captain [Tom Lockyer] suffered cardiac arrest on the pitch, but was responsive by the time he was taken off on the stretcher," the club said.
"He received further treatment inside the stadium, for which we once again thank the medical teams from both sides.
"Tom was transferred to hospital, where we can reassure supporters that he is stable and currently undergoing further tests with his family at his bedside."
Luton and Bournemouth players took to the pitch following confirmation that the game had been abandoned and applauded the supporters.
Lockyer also collapsed during Luton's play-off final win against Coventry in May, when he was taken to hospital for treatment.
He was given the green light to return to football in June after undergoing heart surgery.
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