CINCINNATI , Ohio (REUTERS) - Bulgarian seventh seed Grigor Dimitrov beat Feliciano Lopez 7-6(5) 6-4 at the Cincinnati Open on Wednesday (Aug 16) to set up a last-16 clash with Juan Martin Del Potro.

Dimitrov, who beat Lopez in the second round here last year, nearly broke the unseeded Spaniard three times prior to making a strong start in the tiebreak and went on to finish the match with 27 winners.

"Early on, he was serving very well," said Dimitrov.

"It was just important for me to stay in the game and just put as many returns in as I could in order to get in the rally because as soon as that was happening I felt I had a pretty good chance of winning every point."

Next up for Dimitrov will be Del Potro, who is playing at Cincinnati for the first time in four years, after reaching the semi-finals in 2012 and 2013.

The 28-year-old Argentine booked his spot in the next round with a 6-4 6-4 win over Mitchell Krueger, breaking the American qualifier at the end of both sets to wrap up victory in one hour, 40 minutes.

Del Potro, who on Tuesday upset 10th-seeded Czech Tomas Berdych, also saved five break points at 3-3 in the second set and clinched his 18th victory of the year on his fourth match point.

Dimitrov has not beaten Del Potro in five career meetings, with the most recent defeat coming at Rome in May.

Australian Nick Kyrgios beat Ukraine's Alexandr Dolgopolov 6-3 7-6(6) to reach the third round, where he will face unseeded Croatian Ivo Karlovic.

Also advancing to the round of 16 were Spaniards David Ferrer and Pablo Carreno Busta and Russian Karen Khachanov.

Top-seeded Spaniard Rafa Nadal will cap off the evening session later on Wednesday when he meets Frenchman Richard Gasquet at the Lindner Family Tennis Centre.