Aside from Rafael Nadal's straight-sets defeat in the third round, perhaps the biggest shock at this year's Shanghai Masters has been the surprise run of 21-year-old Japanese player Kei Nishikori, who defeated Jo-Wilfried Tsonga on his way to a semi-final place opposite Andy Murray.

But who is Kei Nishikori? Sports Mole takes a look at his career to date.

Born December 29, 1989 in Shimane, Japan, Kei Nishikori first took to the racket when he was just five. Recognising the potential in their son, his parents sent him to train at the Nick Bollettieri Tennis Academy in Florida when he was 14.

In 2006 he progressed as far as the quarter-final of the Junior French Open, but won the doubles competition, and in the following year qualified for his first ATP main draw event - the Countrywide Classic - at the age of 17.

Defeat followed but he quickly moved on to the Indianapolis Tennis Championships, where he became the youngest player to reach the quarter-final since Boris Becker in 1985.

In 2008 he defeated Florian Mayer on the way to winning his first ATP event, the Delray Beach tournament. In so doing he became the first Japanese man to take an ATP title in 16 years - and he was still only 18.

The same year saw debuts at Wimbledon (retired in first round) and the US Open, where he defeated David Ferrer to reach the fourth round. He was then ousted by Juan Martin del Potro in straight sets.

In 2009 Nishikori suffered a first round defeat at the Australian Open, then suffered a major setback as an injury to his right elbow ruled him out of the French Open, Wimbledon and the US Open.

Returning last year, he notched up a win at the Sarasota Open before competing in his first French Open, where he was ousted in the second round by one Novak Djokovic. Moving on to the US Open, he advanced as far as round three, his second best showing in a Grand Slam.

In 2011, as he turned 21, he entered the Australian Open and defeated Mayer once again. He progressed as far as round three, where he suffered defeat at the left hand of Spain's Fernando Verdasco. Runs at the French Open (round two), Wimbledon (round one) and the US Open (retired in round one) helped Nishikori rise to a career high ranking of 46, a joint record for a Japanese man.

Now, having advanced to the semi-final of the Shanghai Masters, he will break that record when new rankings are unveiled on Monday. But what next? Asked that very question in a recent interview, Nishikori replied: "I want to be number one... that's my goal. I think there are a lot of things I have to do. But for now, this year, I want to get top 30 if I can. Yeah, top 30 is my next goal."