Elite players led by world number one Roger Federer expressed their surprise and concern at the Cincinnati Masters on Wednesday that Rafael Nadal will be forced to miss the US Open due to left knee tendinitis.
"It's not a surprise, because I wrote him and he told me it wasn't looking good at all," said top seeded world number one Federer.
"I kind of saw it coming. But obviously when its official it's disappointing for tennis, there's no doubt about it.
"I would love to have him in the draw. With 12 days before the Open you figure he might still have time to fix what he has to fix to get ready.
"If he pulls out that early before the Open, it must be something serious. That's what is sort of scary.
"There is obviously the whole debate going on if he is going come back for this year.
"I hope in hindsight this is a very smart decision by him. But it's obviously a big blow and disappointing news for the tennis world."
Those sentiments were echoed by number two Novak Djokovic and fourth-ranked Olympic gold medallist Andy Murray.
Venus fights back
Venus Williams fought back from a set down to beat South Africa's Chanelle Scheepers 2-6 6-3 6-2 as the top seeds advanced with little trouble at the Cincinnati Open on Wednesday.
Williams will now meet Italian Sara Errani for a quarter-final berth following the seventh seed's 6-4 6-4 win over Slovakian Daniela Hantuchova.
Federer crushed Alex Bogomolov, of Russia, 6-3, 6-2 to enter third round. Second seed Novak Djokovic made a scratchy start while Andy Murray motored through as the pair of seeds won their opening matches after first round byes.