At one stage in 2011 former US Open champion Juan Martin del Potro was ranked 485 in the world because of a wrist injury that kept him out of action for several months.
Fast-forward to the end of this year and the Argentine has risen up to seventh after a series of impressive performances.
It all began during January's Sydney Open with a quarter-final defeat to Cyprus's Marcos Baghdatis. Next up was the first Grand Slam of the year in Australia, where he reached the final eight before being knocked out by Roger Federer.
Despite the disappointment of that loss, Del Potro was now pushing towards the world's top ten.
February got underway with a defeat in the final of the Rotterdam Open to Federer. However, he soon picked up his 10th career title with a victory over Michael Llodra in Marseille.
By the time March came around, Federer was becoming a real problem for Del Potro. The world number two again defeated 'Del Boy', this time in the quarter-finals at Indian Wells.
Once again he reached the quarter-finals of a Slam but once again he ran into Federer. This defeat really hurt Del Potro because he took a two-set lead before being pegged back by the 17-time Slam winner 3–6, 6–7, 6–2, 6–0, 6–3.
A couple of weeks later at Wimbledon he exited the competition in round four to Spain's David Ferrer. At the same venue in August and September at the London Olympics he fared much better though. Despite losing once more to Federer in the semi-finals, he defeated Novak Djokovic to claim a bronze medal for Argentina.
Del Potro and Djokovic met again at the US Open quarter-finals, with the latter coming out on top on this occasion. Despite failing to make a Slam semi-final, many regard Del Potro's performances in the main events as a success.
With the major tournaments completed, Del Potro went on to win titles in Vienna and Switzerland. The second one will have given him greater pleasure by virtue of the fact that it came against Federer in front of his home crowd.
He beat Federer again at the ATP World Tour Finals in November to ensure that he reached the semi-finals of the competition. It looked as though he was going to reach the final when he led Djokovic by a set and a break. However, the world number one battled back to knock out the Argentine.
Del Potro may have only collected four titles, with none of them being Slams. However, had you offered him that 18 months ago, there's little doubt that he would have taken it!