World number one Novak Djokovic has hardly broken a sweat during his US Open title defence after he defeated Jerzy Janowicz in a four set battle in the first round on Monday, a beneficiary of a walkover in the second round as Jiri Vesely was injured, and two-time US Open semifinalist Mikhail Youzhny retired during the first set in their third round encounter on Friday.

The 12-time Grand Slam champion was sluggish in his opening round match with Janowicz and he required medical treatment for his arm. Nonetheless, following Youzhny's retirement, he stayed in the Arthur Ashe Stadium to get more practice, as he had four days off to prepare for his third round match.

Djokovic's win over Youzhny was his seventh win over the Russian, in their first  meeting since the quarterfinal of the US Open in 2013.

Djokovic starts brightly

The two-time US Open champion served to love in the opening game of the match placing two forehand winners in the corner, and a good first serve out wide, coupled with a forehand unforced error from Youzhny's racquet gave the Serb a comfortable start to the match.

However, Youzhny, currently ranked at a lowly 61 in the rankings, was under immense pressure from Djokovic's groundstrokes in extended rallies. A backhand unforced error handed the defending champion's first break point opportunity.

Surprisingl,y the world number one couldn't capitalise on a second serve and a tame backhand unforced error let Youzhny off the hook temporarily.

Djokovic in action in the Arthur Ashe Stadium (Photo by Alex Goodlett / Getty Images)
Djokovic in action in the Arthur Ashe Stadium (Photo by Alex Goodlett / Getty Images)

An amazing 23 shot rally followed with the Russian coming out on top with a sweet backhand down the line to bring up a game point. But he failed to take it with a forehand winner coming from Djokovic's racquet, followed by a backhand volley winner at the net to create a second break point which the Serb capitalised on with a tame backhand error in the net by Youzhny.

The world number one consolidated the break with ease, and Youzhny finally got on the board with an easy service hold of his own but still trailed 3-1.

Injury problems hit Youzhny

Unfortunately, the Russian called for the trainer after his service game, and the world number one held to love to extend his lead to 4-1.

The former world number eight received a medical timeout for his hamstring and upper thigh area, furthermore, he continued to carry on in the match for a short time.

Youzhny receiving treatment for his hamstring (Photo by Elsa / Getty Images)
Youzhny receiving treatment for his hamstring (Photo by Elsa / Getty Images)

Youzhny was able to hold serve but he called it quits as he was physically unable to compete at 100 per cent. Therefore, the reigning US Open champion secured his tenth consecutive fourth round berth at Flushing Meadows with a 4-2 lead in just 31 minutes.

Match stats

Both players produced six winners each, and the Serb was comfortable on his first serve by having a flawless 100 percentage of first serve point won and he won 80 per cent of his points on his second serve.

Djokovic and Youzhny following the conclusion of Youzhny's retirement (Photo by Elsa / Getty Images)
Djokovic and Youzhny following the conclusion of Youzhny's retirement (Photo by Elsa / Getty Images)

Next for Djokovic

Djokovic will face 20th seed John Isner or Britain's Kyle Edmund in the fourth round of the US Open on Sunday as the Serb continues to his quest to win his 13th Grand Slam singles title, and looks to find his best tennis throughout the tournament.