The fourth seed had a tougher time against Fritz than eighth seed Kevin Anderson did against Philipp Kohlschreiber, with the German served into straight-sets submission 6-3, 7-5, 7-5. He came down with a stomach bug that affected him during his two-day, five-set victory over Taylor Fritz of the U.S.in the second round and felt exhausted down the stretch against Gulbis.
It was unclear if the 21-year-old was still struggling with the problem when he took to Court 1 against Gulbis.
"I think I can be very happy today", said Federer, who will next face France's Adrian Mannarino. Yesterday I had pain during the whole three sets.
"Today in the warmup I was actually maybe thinking about it, not to play at all".
"This is only my second serious tournament back", said Williams, who is returning from a maternity leave. "It's the most special court for me, hundreds of thousands must have come to see me play here". "I hope he's going to go even further in the tournament".
After splitting the first two sets Gulbis served for the third at 5-3. It felt like somebody just unplugged me in the middle of the fourth set'.
Despite a string of wins on the ATP tour, including in Madrid and Munich this year, his form at the French Open and having reached the fourth round of Wimbledon last year, this latest defeat would seem to be a major setback.
"I think he's a future grand slam victor", Gulbis said.
"I didn't think I could win after the first win but he got exhausted in the end".
Three-time victor Novak Djokovic made the last 16 of a Slam for the 44th time with a 4-6, 6-3, 6-2, 6-4 win over Kyle Edmund, the last remaining Briton. "It really messed with me for two balls, then I tried to just calm down, to play my game".
Gael Monfils eliminated last year's semi-finalist Sam Querrey, winning 5-7 6-4 6-4 6-2 to progress to the fourth round at the All England Club for the first time in his career.
The best Grand Slam showing for Gulbis was a run to the semifinals at the 2014 French Open, which included a win against Roger Federer.
Estonia's top tennis player Anett Kontaveit (WTA 27) won against USA tennis player Jennifer Brady (WTA 74) on Thursday, advancing to the third round of the Wimbledon tennis tournament.