The top six seeds all safely progressed through to the third round at the Cincinnati Masters to keep their US Open preparations on track.
Eight of the world's top 10 players are in Ohio ahead of the final grand slam of the year, which starts at Flushing Meadows on August 30, and world number one Rafael Nadal led a good day for the more-fancied names with a comfortable 6-2 7-5 win over American qualifier Taylor Dent.
Roger Federer had an even easier ride through to the next round after Denis Istomin retired after 36 minutes of their match with the Swiss leading 5-2.
Second seed Novak Djokovic saw off the challenge of fellow Serb Viktor Troicki 6-3 7-5 to record his 100th victory at a Masters 1000 event and set up an enticing meeting with David Nalbandian, who won through after John Isner retired from their match leading 5-4.
It was not all plain sailing for the top-ranked players, however, as fourth seed Andy Murray was pushed to three sets before overcoming 58th-ranked Frenchman Jeremy Chardy 6-3 6-7 (7/3) 6-2.
Fifth seed Robin Soderling needed to come from a set down to beat former world number one Lleyton Hewitt 4-6 6-3 7-5 while Nikolay Davydenko (sixth) was also pushed all the way by Robby Ginepri 6-2 6-7 (7/5) 6-2.
Spain's Fernando Verdasco, the eighth seed, was the highest-ranked player to fall as he was beaten by wildcard Mardy Fish 7-6 (7/1) 7-6 (7/4).
Big-serving Latvian Ernests Gulbis also sprung a surprise as he fired down 21 aces to beat 13th seed Jurgen Melzer 6-7 (10/8) 6-3 7-6 (7/5) and book a third-round meeting with Murray.
Ninth seed Andy Roddick did just about enough to beat world number 50 Thiemo de Bekker 7-6 (7/4) 6-4 while David Ferrer (10) survived a tough-looking encounter with 21st-ranked Sam Querrey 7-5 6-2.
World number 32 Julien Benneteau will play Nadal in the next round after he beat Stanislas Warwinka 6-4 6-2, while Germany's Philipp Kohlschreiber earned himself a shot at Federer after recovering from a terrible second set to beat qualifier Alejandro Falla 6-0 1-6 6-3.
France's Richard Gasquet progressed with a 6-4 6-2 win over Michael Berrer.