Seven-time winner Federer progressed after Ukrainian opponent Alexandr Dolgopolov stopped playing due to an ankle injury when trailing 6-3, 3-0 after 43 minutes.

It proved to be a particularly frustrating afternoon for the Centre Court crowd as they had earlier seen a near identical outcome in the match between three-time champion Djokovic and Martin Klizan.

The Slovakian had pulled out with calf problems when 6-2, 2-0 down after 40 minutes. 

"You never like to end up a match this way," Djokovic said.

"You could see he [Klizan] wasn't moving - once the ball was a couple of feet away from him, he let it go."

Djokovic will now face Czech Republic's Adam Pavlasek in round two while Federer will be up against Dušan Lajović of Serbia.

There was a full match for the crowd to enjoy in the women's draw as world number one Angelique Kerber was forced to battle hard before a 6-4, 6-4 win over American qualifier Irina Falconi.

The German will next play Belgium's Kirsten Flipkens.

Third ranked Czech Karolina Pliskova enjoyed serene progress by producing nine aces in a 6-1, 6-4 thrashing of Russia's Evgeniya Rodina. 

Poland's ninth seed Agnieszka Radwanska won 7-6 (3), 6-0 over Serbia's former world number one Jelena Jankovic.

But 16th seeded Russian Anastasia Pavlyuchenkova crashed out after losing 3-6, 7-6 (6), 9-7 against Australian qualifier Arina Rodionova.

Argentina's Juan Martin del Potro and Canada's Milos Raonic were among other men's singles winners today.

Twenty-ninth seed del Potro, the men's singles silver medallist from Rio 2016, overcame a battling Australian Thanasi Kokkinakis 6-3, 3-6, 7-6 (2), 6-4 while last year's finallist Raonic beat Germany's Jan-Lennard Struff 7-5 (5) 6-2 7-6 (4).