Nole is through to the last eight of the US Open at Flushing Meadows without dropping a set.
World no.2 was leading against no.18 seed Stanislas Wawrinka 6-4, 6-1, 3-1 in their rain-delayed clash, when the Swiss retired due to injury.
The match resumed at 2-0 in the first set, having been rained off the night before. The set featured five breaks of serve, Nole built on his overnight lead and won it 6-4.
He raced to a 5-0 lead in the second set and closed it 6-1 in 31 minutes.
The defending champion was a break up in the third set when Wawrinka was forced to retire.
“It’s an unfortunate situation that happened with him, but I felt that I was hitting the ball well in the last two sets before that happened,” said Djokovic. “Hopefully I can keep that going for the next match.”
Novak hit four aces and served at 66 per cent. He had 20 unforced errors to Wawrinka’s 29, and 23 winners to his opponent’s 14.
The 25-year-old Belgrade native converted six of his seven break point chances, while Wawrinka capitalised on only two of his six opportunities.
In his 14th successive Grand Slam quarter-final appearance, Novak will play against 7th-seeded Juan Martin del Potro.
The Argentine beat no.20 seed Andy Roddick 7-6, 6-7, 2-6, 4-6. It was the American’s final career match.
Djokovic and DelPotro have met seven times, Nole leads 5-2.
Their quarter-final encounter is scheduled on Thursday about 20.30 local time (Friday about 02.30 CET).
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