"The pain in the shoulder embarrassed me in the service and in reverse", acknowledged the world number one, who has several times the doctor on the court to be massaged.
"It's been a while since I hurt this shoulder. I have to do with and know how to seize every opportunity"he added, saying he was going"block his arm during the two days of rest ahead", hoping to be at best for his next match.
He will face Friday for a place in the 8th finals fellow Serbian Dusan Lajovic (29th) or the American Denis Kudla (111th).
Under the roof of Arthur-Ashe court closed for rain, Djokovic was hooked to the score in the second run. But, considering his shoulder pain, he confessed that the match had been "very difficult with a lot of long exchanges."
"He did not have a chance at 3-0 and double break in his favor in the second set when I managed to come back", he explained about his opponent."This second set was crucial", he added.