Djokovic and Federer progress
Novak Djokovic and Roger Federer were comfortable winners at the Western & Southern Open.
World number two Djokovic defeated Andreas Seppi of Italy 7-6 (7/4) 6-2 on a court baked in sunshine and 86-degree heat.
The Serbian said afterwards: "Sometimes it's really hard to try to stay fit for every single tournament and try to perform your best.
"In the last three, four weeks, I have changed three different cities, places, surfaces, conditions. I'm still trying to figure out where I am."
Elsewhere, 10th seed Mardy Fish advanced to the third round by defeating Argentina's Carlos Berlocq 6-3
6-1, Serbian Victor Troicki progressed with a 6-2 6-0 win over Australian Lleyton Hewitt, while Russia's Nikolay Davydenko beat Germany's Florian Meyer 6-3 6-3.
Top seed Federer recorded a 6-3 6-2 win over Alex Bogomolov Junior to set up a last-16 clash against Bernard Tomic.
The top-ranked Swiss must make the final in Cincinnati to ensure Djokovic does not regain the world number one ranking.
Fourth seed David Ferrer was a shock departure, losing 6-4 6-1 to Stanislas Wawrinka, while seventh seed
Janko Tipsarevic and Juan Monaco were also third round casualties.
Serb Tipsarevic retired due to heat exhaustion while trailing Spain's Pablo Andujar 6-4 4-1, while Argentina's Monaco was defeated by Czech Radek Stepanek 7-6 (7-2) 6-1.
Sixth seed Juan Martin del Potro ended German veteran Tommy Haas' tournament with a 7-5 6-2 win, while Canada's Milos Raonic was tested before surpassing Cyprus' Marcos Baghdatis 6-7 (6-8) 6-3 6-4.
Kei Nishikori, the 14th seed from Japan, dismissed American wildcard James Blake 2-6 6-4 6-4, and French lucky loser Jeremy Chardy set up a last-16 clash against Murray with a 6-4 6-3 win over Uzbekistan's Denis Istomin.