|Djokovic makes winning US return in Cincinnati as rival retires, Photo: AARON DOSTER / GETTY IMAGES NORTH AMERICA / GETTY IMAGES VIA AFP |
The world number two Serb advanced after winning the first set 6-4, when his Spanish opponent could not go on with a lower back injury.
"He told me it started yesterday," the 23-time Grand Slam singles champion said. "Hopefully he will be ready for New York (US Open).
"This is never the way you want to win, the crowd was expecting a match, a battle," the 36-year-old added.
"I have mixed emotions with how the match ended. I'm hoping to build form and progress through the tournament by raising my level."
Djokovic is playing in the United States for the first time since 2021.
He was barred from entering the country during the latter stages of the COVID-19 pandemic after refusing to get vaccinated.
Djokovic's next opponent on Thursday will be Gael Monfils, who continued his run of comeback form by defeating Australian Alex de Minaur 7-5, 6-4 to reach a third round for the second consecutive week.
The 36-year-old Frenchman excelled as he beat the weekend finalist in Toronto in two hours with 29 winners to 14 for de Minaur.
"It will be a battle of the veterans," Djokovic said of the over-35 clash.
"Gael is an amazing guy, i truly respect and like him - he brings so much joy to fans.
"He's the most charismatic player we've had in the last two decades."
- Sinner slump -
Elsewhere Wednesday, Italian eighth seed Jannik Sinner fell back to earth with a 6-4, 7-6 (7/4) opening loss to qualifier Dusan Lajovic, just three days after winning his first ATP Masters 1000 title in Toronto.
On his 22nd birthday, Sinner lost for the first time this season in an opening round after 13 winning starts.
The 33-year-old Lajovic, ranked 66th in the world was outstanding as he took full advantage of Sinner's fatigue after his efforts in Canada, winning all his 16 points at the net and all five break points he faced.
It was also a disappointing day for fifth seed Casper Ruud, with the Norwegian going down 6-4, 3-6, 6-4 to Australian qualifier Max Purcell, ranked 70th in the world.
Daniil Medvedev started his Cincinnati campaign with a comprehensive win.
The number three backed up last week's victory over Lorenzo Musetti with a repeat performance, dispatching the Italian 6-3, 6-2 after also having beaten him six days ago in Toronto.
Last year's runner-up Stefanos Tsitsipas tamed the upset hopes of American Ben Shelton, defeating the 20-year-old 7-6 (7/3), 7-6 (7/2).
Alexander Zverev, the 2021 champion, moved into a third-round showdown with Medvedev, putting out Japan's Yoshihito Nishioka 7-5, 6-4.
Toronto semi-finalist Tommy Paul was slotted in as the next opponent for top seed Carlos Alcaraz with a 6-1, 7-6 (7/4) defeat of Frenchman Ugo Humbert.
In the WTA draw, world number one Iga Swiatek raced to a 6-1, 6-0 sweep of American Danielle Collins to reach the third round on the first dry day of the week.
The Pole, who lost a Montreal semi-final to Jessica Pegula, defeated Collins last week and took just 61 minutes to do it again.
Top American Pegula relied on an angry racquet smash to reset her game after losing the opening set to Martina Trevisan of Italy.
The third seed, who won the Montreal title at the weekend, reversed her fortunes for a 6-7 (2/7), 6-2, 6-3 win to reach the third round.
"Sorry to my racquet," she said. "I was not so positive today, but the crowd really helped me out.
"It was a super-quick turnaround for me from Canada. Conditions here are very different and that's always going to be trouble. The ball really flies."
Tenth-seeded Wimbledon champion Marketa Vondrousova advanced past Anastasia Potapova 6-4, 6-2. She will next play American Sloane Stephens.
Venus Williams lost to China's Zheng Qinwin 1-6, 6-2, 6-1.