Novak Djokovic is one step close to the calendar grand slam after outlasting Kei Nishikori 6-7(4) 6-3 6-3 6-2.
The world number one survived a three and a half hour battle against the 2014 finalist to reach the second week of the US Open.
Djokovic will now face Aslan Karatsev or Jenson Brooksby in the last 16 on Monday.
In the 20th meeting of their career it was Nishikori who made the brighter start with Djokovic struggling with the half-sun and half-shadow Arthur Ashe Court.
After saving a couple of break points, Nishikori rushed Djokovic’s error-prone backhand and broke for a 2-1 lead.
The former finalist produced a gutsy eight minute hold for a 4-2 lead as he continued to produce punishing shots that were painting the lines.
However eventually Djokovic’s sustained pressure took its toll with some poor decision-making from Nishikori handing the break to the world number one as the opening set was back on serve at 4-4.
Djokovic had opportunities to secure another break but some missed returns allowed Nishikori to hold and force a first set tiebreak.
The three-time champion would pay for those missed opportunities as a perfect Nishikori lob earned him a mini-break at 5-4.
That was the window of opportunity that Nishikori needed to hold his two service points and take the opening set on a frustrated world number one.
A new re-found focus was found by Djokovic in the second set despite the opening set as he broke in the third game for a 2-1 lead which was followed by his trademark roar.
The first of many as Djokovic was forced to save seven break points en route to service holds as Nishikori’s level of returning went up a notch.
However it was Nishikori’s turn to pay the price for not taking opportunities and Djokovic secured a second break of serve to level the match at one set all.
From then on it was a mature Djokovic performance who grinded Nishikori down with his deep and consistent groundstrokes.
The Serb’s backhand had grown in confidence as he took a 4-1 lead as he was cruising to a two sets to one lead.
Despite Nishikori getting the break back in the seventh game, the world number one won the next two games to seal the third set and yes, another roar followed.
Two breaks in the fourth set sealed a three and a half hour victory against a resilient Nishikori and one step closer to a history-making calendar grand slam.
Djokovic now awaits the winner of Aslan Karatsev or Jenson Brooksby in the last 16.
