Macci, who coached the Williams sisters in their childhood, has followed Gauff for years and he often gives his takes on X (former Twitter) about the American’s game and results. Over the past two years, the 70-year-old called on the American tennis star numerous times to turn to a biomechanics coach to help her fix her serving issue. In one of his recent interviews, Williams’ ex-coach even said that if the world No. 2 hired him and a biomechanics coach, she could easily get to double digit Grand Slam title number.

While Gauff didn’t hire Macci, she made a shakeup just before the US Open after it was revealed on Tuesday that she split with coach Matt Daly and hired biomechanics coach Gavin MacMillan – the same coach who fixed Aryna Sabalenka’s serving woes in 2022.

Macci on Gauff’s second serve after it gets fixed: A grasshopper on steroids

“Everything in life is in the EYE OF THE BEHOLDER. The problems with Coco serve will be signed and sealed and she’ll deliver. Gavin will take a step-by-step science-based approach as he sees many issues from the preparation phase to the cocking phase that has affected the toss spine angle and weight transfer,” Macci wrote on X.

In another post, the 70-year-old tipped Gauff’s serve to reach “a special place.”

Also, Macci directly tipped the current world No. 2 to reach the top spot.

It will be interesting to see if MacMillan can make some quick fixes to Gauff’s serve and help it immediately look better at the US Open.