Net Gains: Federer's challenges are laughable – but not as bad as Gulbis

He wins just about everything else, but one honour Roger Federer will not take away from this year's US Open will be that of best amateur line judge. When it comes to video replay challenges, there are not many players with a worse record than the world No 1. Federer went into his semi-final against Novak Djokovic having made 13 challenges at the current tournament and succeeded with just three. Only John Isner, successful with two out of 14 challenges, had got more wrong among the men. Federer has never liked the system and does not trust it. After one challenge in his quarter-final against Robin Soderling, the Swiss still insisted he was right and Hawk-Eye wrong despite the computer's verdict. Melanie Oudin has been among the worst of the female challengers, failing with all but three of her 16 referrals, while Dinara Safina got only two out of 12 right. Of those who have made more than two challenges, the players with the best success rate have included Robert Kendrick (four out of five), Juan Carlos Ferrero (five out of seven) and Meghann Shaughnessy (three out of four). Andy Murray overturned three out of 10 calls, which is about average on the tour. There have been some lighter moments involving challenges. Ernests Gulbis was so hopelessly wrong with one against Murray that it reduced the two players and the crowd to laughter, while Juan Martin del Potro challenged an "in" call on his own serve, having not reached his opponent's return.

Knickers and knockers

When Taylor Dent played Murray last week, some of the older photographers here recalled, misty-eyed, the day at Wimbledon in 1979 when his mother, Betty-Ann Stuart, a former top-20 player, attracted hordes of cameramen by playing in a pair of knickers bearing the slogan "Watch it". Stuart also played a role in a bigger photo-story at the All England Club that year, when Linda Siegel, a well-built 18-year-old Californian, played in an ill-fitting halter dress against Billie Jean King. The boobs emanating from her racket were not the only ones on view. The dress had been borrowed from Stuart, her doubles partner.

Cilic and Co hit heights

It's official: players are getting bigger. The 'Wall Street Journal' reported last week that the players in the men's draw are an average one inch taller and five pounds heavier than their equivalents 20 years ago. Twenty of the 128 men were 6ft 4in tall compared with 10 in 1989, while 38 (compared with 54) were 5ft 11in or shorter. Most useless statistic of the week: in terms of the combined height of the two players, Juan Martin del Potro and Marin Cilic, both 6ft 6in, equalled the record for the biggest Grand Slam quarter-final in the Open era set by Mark Philippoussis (6ft 5in) and Alexander Popp (6ft 7in) at Wimbledon in 2003.

New record for Murray

Andy Murray has grown accustomed to setting new marks for British tennis, but another record is beckoning. The world No 2 makes a brief singing appearance on the forthcoming new album by the Bryan Brothers Band.

p.newman@independent.co.uk