( CNN ) -- The battle for men 's tennis supremacy in 2012 will boil down to the U.S. Open at Flushing Meadows , according to former world number one Jim Courier . The American Davis Cup captain has watched the world 's top players at close quarters this year and believes there is nothing to divide Australian Open champion Novak Djokovic , Wimbledon winner Roger Federer and Olympic gold medalist Andy Murray . Rafael Nadal would also come into that category , but the French Open champion will miss the New York event with a knee injury which also prevented him taking part at London 2012 . `` The winner of the final slam of the season will have added a second major title to their record and can justifiably claim to be No.1 , '' Courier told CNN 's Open Court ahead of Monday 's opening matches at the two-week hard-court tournament . The four-time grand slam champion said Murray 's Olympic triumph in the men 's singles this month , when where he beat Federer in straight sets in the final , had elevated him to the same status as the other three . `` It used to be three and a half , now it 's the big four , '' Courier said . `` Murray has momentum with him and has been unbelievably consistent . '' But when pressed to predict the winner in New York , Courier opted for defending champion Djokovic , believing he can return to the form which saw him totally dominate in 2011 `` and on his best surface . '' The Serbian started his North American hard court swing by easily retaining his Toronto Masters crown where he beat Richard Gasquet in straight sets in the final . He ca n't reclaim the No . 1 ranking from Federer even if he wins the September 8 final , but it would set him up for the end-of-year honors ahead of November 's ATP World Tour Finals . Murray upbeat about U.S. Open despite crashing in Cincinnati . World No . 4 Murray won his opening match in Canada but then withdrew with a knee injury , and suffered a shock early exit in Cincinnati as he failed to defend his title . With Federer also in superb form , thrashing Djokovic in the Cincinnati final , Courier can not see outside the top three seeds . But he nominated 2009 champion Juan Martin Del Potro , who took Olympic bronze at Wimbledon , French world No . 6 Jo-Wilfried Tsonga and John Isner , who has performed heroics in the U.S. march to the semifinals of the Davis Cup , as dangerous outsiders . `` You would not have any of those in your part of the draw , '' he said . For Courier , who won two Australian Opens and two French Open crowns , the choice of women 's champion is easier . `` Serena Williams , '' said the 42-year-old , who lost in the finals of the 1991 U.S Open and Wimbledon two years later . `` She played ridiculously well in the Olympics . '' Wimbledon champion Williams will be bidding for her fourth U.S. Open crown and 15th grand slam title , but she surprisingly lost to Australian Samantha Stosur in last year 's final when looking similarly invincible . She also slipped up in the WTA event in Cincinnati this month with a quarterfinal loss to Angelique Kerber -- her first defeat since exiting early at the French Open in June . After the U.S. Open , Courier will take the U.S. team to Gijon to face Davis Cup champions Spain as the Americans bid to reach the final for the first time since 2007 . They thrashed Federer 's Switzerland team 5-0 in February and beat Tsonga 's France 3-2 in April . `` We 're not going to beat the Spaniards -- but we were n't going to beat the Swiss or the French either , '' Courier said . `` You look on paper at our matches this year -- away , on clay , against great teams -- we should be playing a relegation match now rather than the semifinals . `` The Bryan brothers , they 've won everything , done everything . Isner 's been a real threat to everyone he 's played in Davis Cup and Mardy Fish came up big for us in Switzerland with a singles win and doubles win . We 've put together a true team effort . '' Courier will be taking on some of the finest tennis players in modern history in the 12-city Powershare Champions Series that he helped create . John McEnroe , Andre Agassi , Jimmy Connors and Michael Chang will be among the big names taking part in a whistlestop tour of the U.S. from mid October to the end of November .
U.S. Open next month pivotal in deciding player of year in 2012 . Four different winners of men 's grand slams and the Olympic singles crown . The top three players from each continent will be seeded into a final four to determine who goes on to play for gold at London 2012. He believes Serena Williams overwhelming favorite for women 's crown .