Coco Gauff has enjoyed a strong season on the WTA Tour, although it’s been far from perfect…
The American star won her second Grand Slam earlier in the year, when Gauff defeated Aryna Sabalenka in the French Open final.
She was, however, unable to carry that form through to the remaining two major tournaments of 2025.
Gauff lost to Dayana Yastremska in the first round of Wimbledon and to Naomi Osaka in the US Open last 16, finishing the year with a 14-3 record at Grand Slams.
Before the US Open began, Gauff brought in Gavin MacMillan, a serving expert, replacing her former coach, Matt Daly.
The move was criticized at the time, and has now come under scrutiny once more, as Gauff’s fellow American, Ryan Harrison, tells her she needs to be smarter.
Ryan Harrison says Coco Gauff made a mistake changing coaches on the eve of the US Open
Speaking to Sky Sports, Harrison gave his verdict on Gauff’s serving struggles and her decision to replace Daly with MacMillan.
“She has won in spite of her serve. She is so good from the back of the court and is such a good athlete that she gets to a place where she is throwing her first serve in at 75mph and still winning majors and matches,” he said.
“How do you improve it?
“Well, you don’t do what she did at the US Open, which is bring in a serve guru right on the precipice of the US Open, when all eyes are on her. You have to be smarter than that.”
Harrison believes the move backfired on Gauff physically and mentally.
“For her team to bring in someone who is a serve expert and then to be out there serving for 45 minutes on every off day, you are going to kill your shoulder if you are resting up for Grand Slam tennis and everybody’s eyes are on her,” he said.
“Okay, she has already been on the biggest stages, but she is in her early 20s and is dealing with all this pressure.
“She won a match at the US Open and was in tears in the middle of the match because of everything that was going on.
“To put that sort of pressure on her by bringing in a serve expert, do that in the off-season, do that away from the lights. Why bring in someone like that? I don’t understand.”
The 33-year-old explained how he wants to see Gauff approach things differently in the future.
“If you are a Slam champion, you don’t want to let everyone know there is a problem. You don’t want to go and put it on a poster,” said Harrison.
“You have this invincibility about you in the locker room where nobody knows what is going on.
“I would love to see her go down the route of I am still Coco Gauff, I am still going to take it to you, even if I am not serving my best right now, I am going to figure it out.
“But she made it such a thing, I feel it really affected her mentally as well.”
Harrison was also perplexed by Gauff’s decision to replace Daly, with whom she had won a Grand Slam just months earlier.
“This is interesting because she fired her coach less than three months after a Grand Slam,” he said.
“If I am coaching someone and they win a Slam and I don’t have a job three months later, I am thinking something crazy has to have happened behind the scenes.”
Gauff has certainly received her fair share of criticism since making the change, but has her serve improved since hiring MacMillan?
Coco Gauff’s serving stats before and after hiring Gavin MacMillan
Comparing the three tournaments Gauff played before hiring MacMillan, and the three tournaments she’s played since, it’s clear to see that the decision to work on her serve has paid off.
Coco Gauff’s serving averages before hiring Gavin MacMillan
| Tournament | Aces | Double faults | 1st Serve % | Win % on 1st Serve | Win % on 2nd Serve |
| Wimbledon | 2 | 9 | 45% | 69% | 61% |
| Canadian Open | 3 | 14 | 52% | 68% | 67% |
| Cincinnati Open | 4 | 9 | 68% | 67% | 37% |
| Average | 3 | 11 | 55% | 68% | 55% |
Coco Gauff’s serving averages since hiring Gavin MacMillan
| Tournament | Aces | Double faults | 1st Serve % | Win % on 1st Serve | Win % on 2nd Serve |
| US Open | 3 | 7 | 68% | 65% | 65% |
| China Open | 3 | 6 | 69% | 62% | 60% |
| Wuhan Open | 3 | 5 | 70% | 68% | 68% |
| Average | 3 | 6 | 69% | 66% | 64% |
In three of the five key serving metrics, Gauff has improved on average since MacMillan joined her team.
While the move may not have done her any favors at the US Open, perhaps it will be worth it in the long term.
Only time will tell if her serve will hold up when she begins her WTA Finals campaign against Jessica Pegula on Sunday, November 2.
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