ANALYSIS: Why is Coco Gauff's second serve so unreliable?

Coco Gauff has failed to hit the heights she achieved back at the start of June, when she won her first Roland Garros title. After being knocked out in the Cincinnati quarter-finals, there are a lot of questions being asked about one specific part of her game.

The American number one had a bitterly disappointing but brief grass campaign, playing and losing two games in Berlin and Wimbledon. She attempted to bounce back at the Canadian Open, but after sneaking past fellow American Danielle Collins and Cincinnati semi-finalist Veronika Kudermetova, she was halted in her tracks by an 18-year-old Victoria Mboko, who not only knocked out the number one seed but went on to win the event, attracting attention from the whole tennis world.

With her home Grand Slam coming rapidly up, Gauff was in need of a good run to fine tune her preparations for the event where she won her first Grand Slam as a 19-year-old. She got past Xinyu Wang and Lucia Bronzetti, with a bye sandwiched between those victories.

One notable thing in these ties was that her serving was not up to par. She hit eight doubles faults in the win over Wang, but that would only be half of what she would rack up in the quarter-final defeat against Jasmine Paolini, in a repeat of the Rome final earlier this year. In a low-quality game involving 14 breaks of serve, it was the Italian who moved on, while Gauff was punished for her lacklustre serving display.

The 16 double faults from her last game are not a one-off stat for Gauff. In the victory over Collins in Montreal, she struck a staggering 23 double faults, the fifth highest in a WTA tour match. Her tally has been extended to 293 this year with an average of 6.11 per match. According to Sliding Backhand on X, Gauff has played 19 matches this year where 10% of the points on her serve have ended in a double fault, with the issue cropping up much more recently, with 12 in the last 17 boasting that unpleasant stat.

This follows on from last year, where she struck a total of 430 double faults, the fourth highest in WTA history, only behind Jelena Ostapenko with 436, Marion Bartoli, who hit 437, and Camila Giorgi, whose 458 double faults in 2015 place her top of the list. She also leads the tour in double faults, having failed to find the opponent's service box 250 times in 41 matches, 57 more than the next tennis player.

All of this raises the question: why is Gauff's second serve so unreliable? It is partly to do with her technique, with an inconsistent preparation heading into the serve, whether that is a poor ball toss or slack racquet timing. It is also to do with her body movement, unable to rotate her body or position her feet correctly to produce the cleanest serve. The American may also struggle with the mental side, fully aware of the mistakes she is making and putting herself under needless pressure not to do it again, culminating in more.

Despite these deficiencies, she has proved that she can still compete at the top level. In the Roland Garros final, she hit eight double faults and won only 50% of her second service points. She still went on to claim the title. Although last year her serving problem was bad, she still went on to claim the WTA finals. Still in number two in the world, Gauff has to find a way of improving her serve so ties such as Paolini do not keep regularly occuring.