Andy Murray will hope he can at last trust his body when he plays Matthias Bachinger at the US Open on Thursday.
Fourth seed Agnieszka Radwanska became the first major casualty of the US Open when she was dumped out by Peng Shuai.
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.
Eugenie Bouchard showed again she is a different animal at the grand slams with a 6-2 6-1 victory over Olga Govortsova.
Andy Murray feels he is "playing with the house's money" after his narrow escape against Robin Haase at the US Open.