Vonk has revealed his disdain for the World Cup ball, dubbed ‘Jabulani’, which will be used in the 64 games at the tournament.
“It is claimed the ball holds its line exactly, but in reality it veers off in all directions,” he lamented. “The ball is lighter and there seems to be more plastic used than previously.
"It is a tragedy for goalkeepers."
But the ball is not the only issue that will trouble goalkeepers, Vonk claims.
He believes that playing at altitude could cause some goalkeepers chronic problems, especially as some of the stadiums are at lower levels.
“Between the stadiums in Cape Town and Johannesburg, there is a 1,696-metre altitude change,” he said. “If you need your goalkeeper in the World Cup, you should examine the geographical circumstances.”