Michael Olaitan has begun full training with his Greek club Olympiakos following an eight-month injury layoff.
The 21-year-old collapsed during a league game in March but regained consciousness before reaching hospital for tests.
Club doctor Christos Theos initially said a viral infection had caused the incident, which occurred while the Nigeria international was running off the ball.
The Greek club were adamant Olaitan, who prior to injury was in contention for a 2014 World Cup appearance, would not be rushed into training until further tests were carried out. They eventually confirmed his return on Thursday.
“All the players were involved in the full training session, Olaitan also trained with the main group on Thursday,” Olympiakos announced on its website.
The player has expressed relief at his recovery, saying: “I’m beginning to feel my body responding. I feel great but will take it one step at a time.
“It’s very important that I try and be patient, but I’m really happy with my progress.”
Olaitan played for Nigeria at the Fifa U-20 World Cup in 2013. He scored a total of 8 goals in 16 games in the 2013-14 season.