Novak Djokovic used to have a reputation for frailty, a man who could not be relied upon to last the distance. When he retired in the fourth set of his Australian Open quarter-final in January, it was the eighth time in the Serb's senior career that he had thrown in the towel during a match.
As the 2009 season draws to a close, however, you would not think of questioning the world No 3's durability. Djokovic's 6-4, 1-6, 6-3 victory over Robin Soderling in the quarter-finals of the Paris Masters here yesterday was his 74th win in 92 singles matches this year.
He has already played 18 more matches than any other player on the main tour – Rafael Nadal, Andy Murray and Fernando Verdasco are joint second on the list with 74 – and would take his tally for the season to 99 if he won here and successfully defended his title at the Barclays ATP World Tour Finals, which begin at the O2 Arena in London next Sunday. Djokovic's recruitment earlier this year of a new fitness coach – Gebhard Phil-Gritsch, who used to work with the famously strong Thomas Muster – is clearly paying dividends.
Nevertheless, it remains to be seen how much Djokovic has left in the tank for his semi-final today against Nadal. Although the Spaniard has won 14 of their 19 meetings, they are usually hard-fought affairs. Djokovic won the most recent, in Cincinnati three months ago, and kept the Spaniard on court for more than four hours in their penultimate contest at the Madrid Masters in May.
"It's going to be extremely difficult," Djokovic said. "I'll just try to recover physically and get ready for that match. The game that I would like to improve is my serve, which I didn't think was working well today. If my serve works well tomorrow, it will be a big advantage."
No wonder Djokovic admitted that he was feeling tired after reaching the semi-finals here for the first time. Soderling still had a chance of clinching the final place in the eight-man field for London and looked to have turned the match around in the second set, but Djokovic dug deep. Soderling dropped serve when he netted a backhand at 4-4 in the final set and Djokovic completed the job when the Swede missed an attempted drop shot on match point.
With the end-of-season finale in sight, some top players appear happy to make early exits at this stage of the season, but Djokovic said that he gave his best in every match.
"I don't make a difference between tournaments," he said. "I will really always try to get the last piece of energy in my body to win the match. I'm well aware that now I'm not the freshest guy on the tour, but I'll only think about upcoming events when I finish this tournament."
Soderling's defeat and Nadal's 7-5, 7-5 victory over Jo-Wilfried Tsonga handed Fernando Verdasco the last place in the field for London alongside Roger Federer, Nadal, Djokovic, Murray, Juan Martin del Potro, Andy Roddick and Nikolay Davydenko.
Tsonga, who won the title here 12 months ago, had his chances against Nadal. Both men had six break points, but whereas the Frenchman could not convert any the Spaniard twice broke in the 11th game. The world No 2, who came close to losing in his previous two matches, made just eight errors to Tsonga's 37.
In the other semi-final Gaël Monfils or Marin Cilic will play Radek Stepanek or Del Potro, who were meeting in last night's remaining quarter-final matches. Del Potro is closing in on Murray's world No 4 ranking. With substantial points totals to defend between now and the Australian Open, Murray could be overtaken by the Argentinian before next year's opening Grand Slam.