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.

What is wrong with Gauff's serve?

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.