Paraguay’s Fabrizio Zanotti was taken to hospital after being hit on the forehead by a wayward tee shot from Alexandre Kaleka during the first round of the KLM Open in the Netherlands.
The world number 97 was on the 16th fairway when he was struck by the Frenchman’s drive off the 14th.
Play was suspended for nearly two hours as the 31-year-old received treatment.
Fellow players Felipe Aguilar and Ricardo Gonzalez accompanied him to hospital and also withdrew.
Starting on the 10th, Zanotti was level par when he was struck after six holes of his first round at Kennemer on the outskirts of Amsterdam.
European Tour tournament director Miguel Vidaor said: “The latest report from hospital is that all neurological tests have come back clear. We wish Fabrizio a speedy recovery.”
Chile’s Aguilar, who was in the group behind Zanotti, was also level par when he withdrew while Argentine Gonzalez – a further group back – was two over.
Zanotti has enjoyed comfortably his best season on the European Tour, lying 27th in the Race to Dubai prior to the start of the tournament.
