New Zealand boxer David Light suffered a mild stroke and underwent surgery for a blood clot following his world title defeat to Lawrence Okolie, his coach said on Wednesday.
The 31-year-old Light lost on a unanimous decision to Britain's Okolie for the World Boxing Organization cruiserweight belt in Manchester in late March.
The New Zealander reported no ill effects when he flew home but felt unwell in the days after his return, his coach Isaac Peach told reporters.
Light, a 2014 Commonwealth Games silver medallist, was admitted on April 17 to a hospital in Auckland where surgeons removed a blood clot.
He is recovering in hospital but Peach would not be drawn on whether Light will fight again.
"That's for David to answer, not me," said Peach.
In a statement put out by his promoter, Light said his focus was now on recovery.
"This is like another fight camp for me, I've got to train hard, rehab and work on getting better," said Light.
Defeat to holder Okolie for the world title was the first loss of Light's career.
Peach said it had been "devastating" to see his fighter fall ill.
"It's horrible. It's really hard for all of us to see him like that," Peach said.