Evander Sno collapsed during a reserve run-out for Ajax on Monday after suffering a suspected heart attack.
The former Celtic and Bristol City midfielder crumpled to the turf after 63 minutes of a fixture against Vitesse Arnhem.
Reports in Holland claim Sno was revived before being rushed to hospital.
Ted van Leeuwen, chairman of Vitesse, is said to have told reporters that the 23-year-old was in a 'stable' condition when he was taken away by ambulance.
Sno, a former Holland U21 international, joined Ajax from Celtic in 2008.
He returned to Britain to take in a loan spell at Bristol City last season, scoring three goals in 24 Championship appearances.
A statement released Ajax's official website claims Sno has responded to doctors in hospital in Arnhem.