Andy Murray or Novak Djokovic: After Rafael Nadal's exit, who is the favourite to win US Open 2016?

After Rafael Nadal's fourth-round exit from US Open 2016, the final at Flushing Meadows is likely to be played between Britain's Andy Murray and Serbia's Novak Djokovic.

Murray has been at the receiving end at numerous Grand Slam finals in the last five years against his old friend, but the Briton certainly has an advantage this year over Novak at Flushing Meadows as the latter's form has been marred with fitness issues of late.

The World No. 1, who opted out of the Cincinnati Masters recently due to an injury in the left hand, hasn't been at his best at the US Open this year.

And much to the dismay of the Nole brigade, Djokovic was stretched to four sets by 247th-ranked Pole Jerzy Janowicz. While the big server could not prove to be a threat for Djokovic, he did manage to make the Serb run for two hours and 37 minutes before losing 6-3, 5-7, 6-2, 6-1.

Also, Djokovic received medical attention on his 'right' hand during the match.

Djokovic isn't used to playing long first-round matches at Grand Slams and he tried his best to convince everyone that the injury was healing at a rapid pace.

"Calling for the medical timeout was just prevention," the 29-year-old told reporters. "It's all good; to be honest, I take it day by day."

"It's getting better and better each day. I'm glad that I'm experiencing that so hopefully, as the tournament progresses, I'll reach my peak."

If at all Djokovic wanted some rest after the match, he wasn't disappointed and would have been delighted with what happened in his next two matches.

He had a second-round walkover as Czech Jiri Vesely withdrew due to injury in the second round, and was leading 4-2 in his third-round match when Russian Mikhail Youzhny retired with a leg ailment.

On the other hand, Andy Murray is undoubtedly the most fit player currently, and going by his current form, he certainly has a great chance of winning another major.

Surprisingly, despite featuring in the 'Big 4' club regularly in the last few years, Murray has just three Grand Slams to his name.

Time and again, Murray has looked a world class player in Grand Slams before reaching finals. But with Djokovic at the other side of the net, someone hits the panic button and despite having all shots in his repertoire, Murray is seen wasting a lot of energy by screaming towards his box - a familiar and frustrating sight for tennis fans across the world.

But with no Roger Federer and an unfit Djokovic in action, Murray would be aware about his chances of winning another major. He recently clinched his second gold medal at the Olympics – something which would have given him much-needed confidence.

When Djokovic's fitness was at its peak, Murray hasn't had to many chances to decode his flexibility on the tennis court. But with each match, it is clear that Djokovic's fitness is nowhere close to what it was in the last few years.

Having said all that, we must not forget the two other players in the tournament, who can give both Djokovic and Murray a run for their money for the final berth.

Juan Martin del Potro and Stanislas Wawrinka, both the players have proved their mettle time and again on the tennis circuit.

However, only one of them will be able to advance to the semis as Del Potro will face Wawrinka in the quarters, after his eighth seeded Austrian rival Dominic Thiem withdrew while trailing 3-6, 2-3 in the second set with a right knee pain despite receiving assistance from the physiotherapist. Interestingly, even del Potro received some medical attention on his right shoulder injury after dropping serve to go 2-1 down in the first set in the same match.

Wawrinka's backhand, has been the most stunning shot in men's tennis lately. On the contrary, del Potro's forehand is a shot, which explodes after landing on the other side of the net. It might have lost its sheen as a result of several injuries the towering Argentine has undergone, it still is good enough to topple the best in the business. Playing his first-round match at Rio last month, Djokovic suffered a shocking defeat against del Potro.

After ending up being the runners-up at Rio Olympics 2016, Del Potro, at 142 in the world, has also become the lowest-ranked man in 25 years to reach the last eight.

If del Potro gets the better of Wawrinka to reaches semis, he would be the lowest-ranked man to do so at a Grand Slam since 237th-ranked Vladimir Voltchkov at Wimbledon in 2000.

Wawrinka, who saved a match point in an epic triumph over Dan Evans in the last round, would however be keen to show why he is still regarded as one of the best. The Swiss has been a semi-finalist in 2013 and 2015 and the fans would relish the contest between these two players for sure.

Most of the players have witnessed several ups and downs in tennis in the last five years, but Djokovic undeniably has been the undisputed king in Grand Slams.

While he is still the favourite to win the last Grand Slam of the year, considering his struggle in the last few months, this is certainly Murray's best chance to add another major trophy to his cabinet.

After being deprived of a Djokovic vs Nadal contest in the semis, given the circumstances, the fans should not be surprised if Djokovic and Murray are not the two players on the court during US Open 2016 men's singles final match.