Andy Murray will hope he can at last trust his body when he plays Matthias Bachinger at the US Open on Thursday.
Maria Sharapova survived an attritional battle against Romania's Alexandra Dulgheru to reach the third round of the US Open.
Fourth seed Agnieszka Radwanska became the first major casualty of the US Open when she was dumped out by Peng Shuai.
Lleyton Hewitt was unable to cause another upset at the US Open as he went down in straight sets to Tomas Berdych.
Roger Federer and Stan Wawrinka have been confirmed in Switzerland's team for the Davis Cup semi-final with Italy.
Roger Federer eased into the second round of the US Open with a workmanlike win over Marinko Matosevic.
John Isner began his US Open campaign with a win over American college champion Marcos Giron.
Heather Watson was shocked by her poor performance against Sorana Cirstea in the first round of the US Open.
Wild card Cici Bellis, 15, stunned Australian Open finalist Dominika Cibulkova in the biggest upset of the US Open so far.
Wimbledon champion Petra Kvitova avoided a repeat of 2011 in emphatic fashion with a 6-1 6-0 win over Kristina Mladenovic.