Cincinnati - American 15th seed Sam Querrey cruised into the second round of the Cincinnati Open with a routine 6-3, 6-0 win over compatriot Stefan Kozlov on Monday on a day when the old guard dominated the younger players.
Wimbledon semi-finalist Querrey, 29, was barely tested by his 19-year-old wildcard opponent in the 51-minute match during which he dropped only four points on serve and did not even face one break point.
"Went out there and just kind of put my head down and went to work, and played a really solid match from start to finish. It felt good," said Querrey, who since Wimbledon has won a tournament in Mexico and reached the Montreal third round.
Querrey will next face the winner of Tuesday's clash between Dutchman Robin Haase and France's Adrian Mannarino.
Ivo Karlovic, who at 38 is one of the oldest players on the ATP Tour, enjoyed a 6-3, 3-6, 7-5 win over Czech 24-year-old Jiri Vesely while Italy's Fabio Fognini, 30, held off Russian youngster Daniil Medvedev 7-6 (7/5), 6-4.
In keeping with the trend of veterans beating youngsters, Spain's Feliciano Lopez, 35, beat 21-year-old South Korean Chung Hyeon 7-6 (7/5), 6-1.
Unseeded Frenchman Richard Gasquet enjoyed a 6-4, 6-4 win over John Patrick Smith of Australia to set up a second-round clash with Rafael Nadal, who is already assured of returning to world No 1 next week for the first time since 2014.
Spain's Fernando Verdasco, 33, however, was not as fortunate as he dropped his first round encounter with slightly younger German Mischa Zverev 6-4, 6-4.
Results on Monday from the WTA and ATP Cincinnati Masters tournament (x denotes seeding):
Tommy Paul (USA) bt Donald Young (USA) 6-4, 7-6 (7/4)
Richard Gasquet (FRA) bt John-Patrick Smith (AUS) 6-4, 6-4
Ivo Karlovic (CRO) bt Jiri Vesely (CZE) 6-3, 3-6, 7-5
Mitchell Krueger (USA) bt Benoit Paire (FRA) 6-2, 6-1
Feliciano Lopez (ESP) bt Chung Hyeon (KOR) 7-6 (7/5), 6-1
Fabio Fognini (ITA) bt Daniil Medvedev (RUS) 7-6 (7/5), 6-4
Joao Sousa (POR) bt Kyle Edmund (GBR) 6-3, 2-6, 6-3
Frances Tiafoe (USA) bt Maximilian Marterer (GER) 6-3, 7-6 (7/2)
Sam Querrey (USA x15) bt Stefan Kozlov (USA) 6-3, 6-0
Mischa Zverev (GER) bt Fernando Verdasco (ESP) 6-4, 6-4
Ramkumar Ramanathan (IND) bt Christopher Eubanks (USA) 6-7 (5/7), 6-1, 6-4
Petra Kvitova (CZE x14) bt Anett Kontaveit (EST) 1-6, 7-6 (7/2), 6-3
Beatriz Haddad Maia (BRA) bt Lauren Davis (USA) 6-3, 6-2
Daria Kasatkina (RUS) bt Aliaksandra Sasnovich (BLR) 6-4, 6-2
Yulia Putintseva (KAZ) bt Verónica Cepede Royg (PAR) 6-4, 3-6, 6-3
Lesia Tsurenko (UKR) bt Anastasia Pavlyuchenkova (RUS) 5-7, 7-6 (8/6), 6-0
Daria Gavrilova (AUS) bt Kristina Mladenovic (FRA x13) 6-0, 7-6 (8/6)
Camila Giorgi (ITA) bt Katerina Siniakova (CZE) 6-2, 6-2
Kiki Bertens (NED) bt Oceane Dodin (FRA) 6-3, 6-0
Taylor Townsend (USA) bt Monica Puig (PUR) 3-6, 6-3, 6-2
Roberta Vinci (ITA) bt Timea Babos (HUN) 7-5, 7-5
Madison Keys (USA) bt Coco Vandeweghe (USA) 6-4, 3-6, 6-3
Carla Suárez (ESP) bt Mirjana Lucic-Baroni (CRO) 6-3, 7-5