Andy Murray will hope to make amends for one of his worst losses of 2011 when he plays Alex Bogomolov Jr at the Western & Southern Open on Thursday.
The American caused a major upset when he beat world number four Murray in Miami earlier this year, and the pair meet again at 1600 BST in Cincinnati.
Bogomolov beat 15th seed Jo-Wilfried Tsonga in round two on Wednesday.
Rafael Nadal plays Verdasco at 1600 BST, with Novak Djokovic and Roger Federer in action later on Thursday.
World number one Djokovic plays Radek Stepanek, while Federer takes on James Blake in the night match.
Following the defeat of top seed Caroline Wozniacki and withdrawals by Serena Williams and Victoria Azarenka on Wednesday, all eyes in the women's draw will be on fourth seed Maria Sharapova when she plays fellow Russian Svetlana Kuznetsova.
Murray suffered another surprise defeat in Montreal last week, going out to Kevin Anderson in his opening match, so wins are vital this week ahead of the US Open later this month.
"The last couple of years I played great in Canada, and I also played LA last year, so I played a lot of tennis going into the US Open," Murray told BBC Radio 5 live after
"I haven't been used to going into the US Open having played few matches. Hopefully, I'll get a few matches here this week because match play is completely different to practice.
"The more matches I can get, the better."