A majority voted at the 1999 AGM to use three different types of ball, depending on the surface. A slow-pace ball, eight per cent larger than standard, will be used on fast surfaces such as grass or indoor carpet.
A faster, harder and lower-bouncing ball will be used on slow surfaces such as clay. The existing ball will be used on medium-paced surfaces.
The experimental introduction of the balls will begin in January 2000, last for two years, and be conducted from club level to the lower reaches of the Davis and Fed Cups.
The ITF's head of product development, Andrew Coe, said: "This is a great step forward. The new, larger ball will, we hope, produce longer rallies, which, for the recreational player, will mean more time playing tennis. It will also reduce the dominance of the serve, which will make tennis more attractive to spectators. It will also offer greater visibility for players and television viewers."
Critics claim the 130mph service speeds in the men's game have reduced the sport to a contest of strength, rather than one of skill and artistry.
The eighth seed and 1996 champion, Alberto Costa of Spain, defeated the American Vincent Spadea yesterday in the quarter-finals of the Swiss Open in Gstaad.
Costa made quick work of the 24-year-old, needing just over an hour to despatch Spadea 6-3, 6-2.
"The quarter-final is never easy," said Costa, looking for his 10th career title. "I stayed calm and I was very focused, but for me it was a more difficult match than the score showed."
Spadea, a notorious giant-killer, had been expected to be a tough opponent for Costa. The American, ranked 29th in the world, felled the top seed and world No 5 Gustavo Kuerten on his way to the quarter-finals.