NEW YORK, United States (AFP) — Novak Djokovic can equal Pete Sampras’s mark of 14 Grand Slam titles when he faces Juan Martin del Potro in today’s US Open final where friendship will be put to one side in pursuit of unfinished business.

Djokovic is into his eighth final in New York where he was champion in 2011 and 2015.

But the 31-year-old Serb has also suffered five heartbreaking defeats in 2007, 2010, 2012, 2013 and 2016.

Del Potro won his only Slam at the tournament in 2009, memorably defeating Rafael Nadal and Roger Federer back-to-back to achieve the goal.

His career then famously suffered an injury-plagued nosedive which pushed him to the brink of retirement three years ago.

For Djokovic, another appearance in the final at Flushing Meadows looked unlikely just three months ago.

A quarter-final defeat at Roland Garros, where he had completed the career Grand Slam in 2016, left him in deep despair, threatening even to skip Wimbledon.

It was the latest setback to his motivation already dealt bodyblows by an elbow injury which forced him to skip last year’s US Open and contributed to a last-16 exit at January’s Australian Open.

But the man hardened by the NATO bombing of Serbia in 1999 showed his inner steel by confounding everybody by racing to a fourth Wimbledon title in July.

Just as at the All England Club, principal rivals Federer and Nadal departed New York earlier than expected, paving the way for Djokovic to eat further into their legacy.

As well as going level with Sampras today, a win for Djokovic would put him just three majors behind Nadal and six back from Federer who is six years older.