Juan Martin del Potro, Alexander Zverev, Marin Cilic, Dominic Thiem, Kevin Anderson and Kei Nishikori also enjoyed the luxury of being able to sit out the first stage of this Association of Tennis Professionals Word Tour Master 1000 tournament. 

Among those to be knocked-out were 14th seed Milos Raonic of Canada, who was beaten by the United States' Mackenzie McDonald.

McDonald won a three set match 6-3, 5-7, 6-3 to progress to the second round where he is due to face Spain’s Roberto Bautista Agut.

Agut won his first round contest in straight sets against Russia’s Andrey Rublev 6-3, 6-4.

The ninth seed, Diego Schwartzman of Argentina also fell in the first round being defeated by American Sam Querrey.

Querrey won 6-3, 6-4 and is set to face compatriot Taylor Fritz in the next round.

Nishikori’s first opponent in the second round is scheduled to be China’s Yibing Wu, who defeated his compatriot Zhe Li 7-6, 6-2. 

The 12th seeded Jack Sock of the US was another to suffer a first round exit to an unseeded player.

Germany’s Peter Gojowczyk won 6-4, 6-7, 6-3 to advance to the next round where he is set to face Hungary’s Marton Fucsovics.

Thiem and Cilic’s second round opponents have also been decided.

Thiem will face Australia’s Matthew Ebden and Cilic will play Chile’s Nicolas Jarry.

France’s Jeremy Chardy will have to take on second seed Djokovic in the next round as he defeated Maximilian Marterer in the first round.

The French player won in straight sets, 6-3, 7-6 to set up the match up with the former world number one.

Greece's Stefanos Tsitsipas triumphed in his first round match against France's Gael Monfils.

Tsitsipas, who qualified for the Next Gen ATP Finals next month, won 7-6, 4-6, 6-4 to progress to meet Russia’s Karen Khachanov.