Top seed John Isner reached the BB&T Atlanta Open semi-finals with a straight-sets win over Australian Marinko Matosevic.
Top seed Fabio Fognini survived a scare as he won through to the semi-finals of the Vegeta Croatia Open in Umag.
Defending champion Mikhail Youzhny crashed out of the Suisse Open after being beaten 3-6 6-1 6-4 by Robin Haase.
Misa Eguchi's surprise run in the Baku Cup was ended by Bojana Jovanovski an the quarter-final stage.
John Isner moved into the quarter-finals of the Atlanta Open with a comeback victory over home favourite Robby Ginepri.
Top seed Fabio Fognini marched into the quarter-finals of the Croatia Open by beating Albert Montanes in Umag.
Mikhail Youzhny made a comfortable start to his Swiss Open title defence after dispatching Frenchman Kenny De Schepper.
Stefanie Voegele served up a second round shock as she dumped top seed Sorana Cirstea out of the Baku Cup.
Andy Murray is set to continue his ground-breaking partnership with coach Amelie Mauresmo.
Reigning Wimbledon men's doubles champions Vasek Pospisil and Jack Sock made their singles mark in the Atlanta Open.