The family of former world boxing champion Hector "Macho" Camacho is facing a decision on whether he should be removed from life support after a shooting in his Puerto Rican home town left him clinging to life.
Doctors at the Centro Medico trauma centre in San Juan found Camacho, 50, had irregular and intermittent brain activity, said Dr Ernesto Torres, the centre's director.
"We can't declare him brain dead," he said. "We're going to ask the people of Puerto Rico to keep praying."
Dr Torres said more tests would be carried out, but warned the prognosis remained grim. "The changes have been more negative than positive," he said, adding that Camacho did not have enough blood coursing through his brain.
Doctors had initially said Camacho was in a critical but stable condition and expected to survive after he was shot in the face on Tuesday night in the city of Bayamon. But his condition worsened overnight and his heart stopped at one point.
The often-troubled boxer, who won super lightweight, lightweight and junior welterweight world titles in the 1980s, was shot as he and a friend sat in a Ford Mustang parked outside a bar. Police spokesman Alex Diaz said officers found nine small bags of cocaine in the friend's pocket and a 10th bag open inside the car.
Camacho's mother Maria Matias, who flew in from New York on Wednesday, will lead the discussion about whether he should be removed from life support, said Ismael Leandry, a long-time friend and former manager who was also at the hospital.
"We just have to wait to see if Macho gets better. It's a hard battle," Mr Leandry said at the hospital.
Camacho's friend, identified as 49-year-old Adrian Mojica Moreno, was killed in the attack. Police said two assailants fled in an SUV but no arrests have been made and no motive has been disclosed.
Camacho was rushed to Centro Medico, where doctors initially said the bullet passed through his jaw and lodged in his shoulder. Dr Torres said the bullet damaged three of the four main arteries in his neck and fractured two vertebrae, which could leave him paralysed if he were to survive.