SHANGHAI – As a vintage season in which the "Big Four” of men’s tennis have shared the major prizes enters its final weeks, Novak Djokovic is chasing an honour that would set him apart – year-end No 1.The Serbian world No 2 saved five match points on Sunday to overcome fierce rival Andy Murray and win the Shanghai Masters, a huge step towards finishing in top spot for the second year in a row.The 25-year-old, who enjoyed one of the finest seasons in tennis history in 2011, ceded his No 1 ranking to Roger Federer after the Swiss won Wimbledon for his 17th Grand Slam title. And he wants it back."It’s my biggest objective in this moment. It’s something I’m aiming for,” said Djokovic, when asked what it would mean to finish at the top for two years in a row."Obviously this (Shanghai win) is going to be a huge confidence boost and also is going to help me in the race for No 1.”It would take an unlikely sequence of events for the Serbian to fail in his quest as he has fewer points to defend in the closing weeks than Federer in the rolling 12-month rankings.A surprisingly sanguine Murray, 25, said he had endured tougher losses despite the agony of the chances that slipped away.Speaking about Djokovic, he said: "He’s been at the top of the game now, likely to finish No 1, that will be two years in a row. Of course, the No 1 player in the world is what you want to get to.”Regardless of who ends the season at the top, Djokovic is likely to face continuing challenges in his bid to be tennis’s alpha male from Murray, Federer and the injured Rafael Nadal.Federer, 31, defied advancing years and his younger rivals to once more reach the top of the rankings this year. On Monday he started his 300th week at world No 1.