Play best-of-three in Grand Slams to keep top seeds fit, says Billie Jean King

Novak Djokovic hits a return during his win over Paolo Lorenzi (EPA)

Billie Jean King believes that men should play best-of-three-sets in all competitions, including Grand Slam events and Davis Cup, in order to prevent the sort of injuries that forced Rafael Nadal to miss the current US Open. Janko Tipsarevic and Gilles Muller, nevertheless, yesterday joined a rapidly growing group of players here grateful to be playing the longer form of the game.

Tipsarevic, who beat France's Guillaume Rufin 4-6, 3-6, 6-2, 6-3, 6-2, and Muller, who beat Russia's Mikhail Youzhny 2-6, 3-6, 7-5, 7-6, 7-6, became the seventh and eighth players this week to win from two sets down.

King's contention is that the modern game is putting increasing physical demands on players. "As a fan, I want to see today's players staying around longer," King wrote in The Huffington Post. "I am going to miss Nadal at this year's US Open and I think sports fans will as well. I still regret the fact that Pete Sampras quit playing at 31 and Stefanie Graf retired at 30. The sport is so much more dynamic today and it is so much harder on the players' bodies than it was when I played.'

In the 1970s only the later rounds of the men's singles at the US Open were played over five sets. There have been calls for a return to such a system, partly because of the number of mismatches early in the tournament. The introduction of 32 seeds at Grand Slam events means the top players are rarely stretched in the first two rounds.

That was the case as Novak Djokovic began the defence of his title here. The world No 2 needed only 73 minutes to beat Italy's Paolo Lorenzi 6-1, 6-0, 6-1 and earn a second-round meeting with Brazil's Rogerio Dutra Silva.

Lorenzi, who won the same number of games when he lost to Djokovic in the Australian Open in January, won only 35 of the 114 points in the match, including just six of the 29 on his second serve. After winning the opening game of the third set, having lost the previous 12 games in a row, he raised his hands in mock celebration.

Britain's Jonny Marray and Denmark's Freddie Nielsen won their first match together since their Wimbledon victory to reach the second round of the doubles. Marray and Nielsen lost first time out at both Cincinnati and Winston-Salem this summer, but were too good here for Italy's Fabio Fognini and Flavio Cipolla, winning 7-5, 6-3.