Admitting that it was a borderline decision, Birkenshaw took into account some poor batting and the fact that the Nevil Road surface played better as the game progressed on day two.
But it concludes that the oil is continuing to break up and disperse underneath the surface, making the emergency of a major oxygen-poor dead zone unlikely.
The 20-year-old has a poor record on clay, winning only four of his 13 matches on the slower surface and failing to get beyond the first round of the French Open in his only appearance in 2006.