Hilversum - Vandals have damaged four greens at the Hilversum Golf Club, briefly delaying the start of play at the European Tour's KLM Open.
Championship director Daan Slooter says parts of the greens at the fourth, fifth, sixth and ninth holes were dug up.
The start of the KLM Open was delayed by 45 minutes on Thursday while staff repaired the damage.
The patched-up grass on the putting surfaces will be treated as ground under repair.
Slooter says security will be "substantially" beefed up following the vandalism.
Top players including Rory McIlroy, Martin Kaymer and Lee Westwood are part of the strongest field ever assembled for the tournament.
It was not immediately clear why vandals attacked the course.