"I was hoping he was feeling better today but he's had a rough one this year and had to pull out a lot of matches", Federer said.
Federer, who hit his 10,000th career ace in the eighth game of the first set, will face either Dusan Lajovic of Serbia or Greek qualifier Stefanos Tsitsipas for a place in the last 32.
Roger Federer's record-breaking 85th match win at Wimbledon did not require much work.
But that was merely the hors d'oeuvres to an extraordinary post-match press conference, in which Tomic conceded that he was disillusioned with tennis, no longer cares whether he does well in grand slams, and didn't appear inclined to put the work in to make the most of his talent. I'm glad I've made that decision, and that I went to Eastbourne, because it was a very positive experience on and off the court as well.
While tournament favourites Murray and Nadal cruised through to the second round, Wawrinka became the first big upset of the tournament, crashing out at the hands of 6-4, 3-6, 6-4, 6-1 at the hands of Russian Daniil Medvedev.
World number one Angelique Kerber, the 2016 Australian and US Open victor, is among the favourites after reaching last year's final, which she lost to Serena. It was the Latvian's first tour-level, main-draw victory since the 2016 French Open. I already achieved my dream to be back here healthy. It will be the first clash between the pair on grass with the previous three meetings played on hard court.
"I'm happy to be back, but this year is completely different for me".
Three-time champion Djokovic reached the second round when Slovakian opponent Klizan quit with a calf injury.
Federer was leading 6-3, 3-0 when Dolgopolov retired. "I talked to the physio and asked what are my risks and he said he could not tell me so I had to decide myself".
Juan Martin del Potro needed seven match points, but he also advanced, beating Thanasi Kokkinakis 6-3, 3-6, 7-5 (2), 6-4.
"For some, they just want to be out there because they feel like miracles happen: maybe the other guy retires, or maybe the other guy is carrying an injury".
- World number 869 Ward is making only his second grand slam appearance.
On Court No 1, last year's men's runner-up Milos Raonic starts the action against German's Jan-Lennard Struff and they will be followed by women's third seed Karolina Pliskova.
Former French Open champion Garbine Muguruza, the 14th seed, defeated Russia's Ekaterina Alexandrova 6-2, 6-4.