Montreal - Top-ranked Novak Djokovic, Andy Murray, Rafael Nadal and Milos Raonic learned the identities of their second-round opponents on Monday after first-round matches at the ATP Montreal Masters tournament.
Top seed Djokovic will start after the bye given to the leading eight seeds when he faces Brazil's Thomaz Bellucci, who worked for two and three-quarter hours to defeat Uruguay's Pablo Cuevas 7-6 (7/4), 4-6, 7-6 (7/4).
The South American fired 14 aces to 11 for Cuevas, with Bellucci forced to save nine of 12 break points.
Djokovic, who has not touched a racquet since beating Roger Federer for the Wimbledon title a month ago, will start in Canada with a 48-3 record that includes six titles in 2015, including the Australian Open crown.
Murray, seeded second and champion in 2010 and 2011, warmed up for his singles start by reaching the doubles second round alongside India's 42-year-old Leander Paes.
The one-off pairing beat Kevin Anderson and Jeremy Chardy 6-3, 6-1 as Murray began finding his feet on the hardcourts after an opening singles loss last week in Washington to Russian Teimuraz Gabashvili.
In singles, the Scot will face Spaniard Tommy Robredo, a winner over compatriot Feliciano Lopez 6-3, 3-6, 6-3 in a battle of 33-year-olds who have competed a combined 21 times in Canada.
Robredo stands a perfect 5-0 in a series first played a dozen years ago. Murray leads Robredo 5-3, and has not lost to the Spaniard in five years.
Nadal and fellow Spaniard Fernando Verdasco joined in the week's doubles lark, defeating 2014 Wimbledon doubles champion Jack Sock and Czech Tomas Berdych 6-3, 5-7, 10-6.
Nadal now must concentrate on a singles start against Ukraine's Sergiy Stakhovsky, who beat Canadian wildcard Filip Peliwo 6-1, 5-7, 6-2. Nadal won his only match with Stakhovsky in Davis Cup two years ago.
Raonic, seeded eighth, is still working on a comeback after May foot surgery that has hampered his game in recent weeks, keeping him off court after skipping Wimbledon.
The Canadian will test himself against Ivo Karlovic after the burly Croatian serving machine beat Poland's Jerzy Janowicz 6-4, 7-6 (8/6) in the first round.
Karlovic is bearing down on an ATP record, having added 18 aces to a career total of 9,964. He now stands just 201 behind historic leader and countryman Goran Ivanisevic (10 183 aces in 895 matches). Karlovic has played 526 matches with an average of 19 per match.
Australian Bernard Tomic, winner of the Bogata title last month, reached the second round with ease over Joao Sousa 6-3, 6-3, while French ninth seed Gilles Simon levelled his record in Canada to 8-8 as he opened with a 6-2, 6-4 victory over Italy's Andreas Seppi.
Simon, a semi-finalist in Canada in 2008 at Toronto, spent just under 90 minutes in advancing to the second round in the major tune-up event ahead of the August 31 start of the US Open.
Gael Monfils, seeded 15th, beat Fabio Fognini 6-3, 6-1 with the Italian treated after the first set for a right wrist problem, receiving a taping and playing on.
Monfils took full advantage of a hampered opponent to advance, saving all six break points he faced and breaking a frustrated Fognini four times.
"I'm happy with my game, I played a solid match," Monfils said. "It was important to me. I wanted to start off this tournament well."
Results on Monday from the first day of the ATP Montreal Masters (x denotes seeded player):
Gilles Simon (FRA x9) bt Andreas Seppi (ITA) 6-2, 6-4
Sam Querrey (USA) bt Martin Klizan (SVK) 6-3, 6-3
Sergiy Stakhovsky (UKR) bt Filip Peliwo (CAN) 6-1, 5-7, 6-2
Thomaz Bellucci (BRA) bt Pablo Cuevas (URU) 7-6 (7/4), 4-6, 7-6 (7/4)
Ivo Karlovic (CRO) bt Jerzy Janowicz (POL) 6-4, 7-6 (8/6)
Tommy Robredo (ESP) bt Feliciano Lopez (ESP) 6-3, 3-6, 6-3
Bernard Tomic (AUS) bt Joao Sousa (POR) 6-3, 6-3
Leonardo Mayer (ARG) bt Chung Hyeon (KOR) 6-3, 6-4
Donald Young (USA) bt Denis Kudla (USA) 6-3, 6-4
Gilles Muller (LUX) bt Philip Bester (CAN) 6-2, 6-3
Gael Monfils (FRA x15) bt Fabio Fognini (ITA) 6-3, 6-1