Australian Open 2025
Dates: 12-26 January Venue: Melbourne Park
Coverage: Live radio commentary on Tennis Breakfast from 07:00 GMT on BBC 5 Sports Extra, plus live text commentaries on the BBC Sport website and app
It is safe to say a player who is aiming to become the youngest man to complete the career Grand Slam does not have many faults.
However, if there was one area where Carlos Alcaraz was weaker than the rest, it was his serve.
The 21-year-old Spaniard and his team, headed by coach Juan Carlos Ferrero, looked to put that right before the new season.
So far at the Australian Open, Alcaraz has been reaping the benefit of his beefed-up serve.
On Wednesday, Alcaraz hit 14 aces in a 6-0 6-1 6-4 second-round win against Japan's Yoshihito Nishioka.
He left a cheeky message on the on-court camera lens afterwards, writing: "Am I a servebot?"
Alcaraz was joking, of course - he will never be John Isner, the 6ft 10in former world number eight who became the prototype 'servebot'.
Nor will he be Reilly Opelka, another skyscraper American who has whacked 78 aces in his opening two matches.
Alcaraz has hit 20 aces in total - putting him in tied 20th in the men's draw - but his ironic message showed he is happy with his serving progress.
In the one-sided victory over Nishioka, the world number three won 89% of first serve points - helped by those aces - and 71% of second serve points.
It was a huge improvement from his opening match and the result of a Tuesday practice session dedicated to serving.
"I felt really good today with the serve," said Alcaraz, who is bidding to surpass Rafael Nadal as the youngest man to win all four majors in the Open era.
"I talked with Juan Carlos about what I have to do today with the serve, what I did wrong and what I did great from the first match.
"I felt more comfortable on it. I think the serve is about confidence and feelings."
While casual tennis fans might not notice the tweaks Alcaraz has made, the hardcore have been paying close attention.
So what has changed?
The service motion looks more relaxed than previously, with a looser wrist action giving him more rhythm.
The start of the serve also seems smoother. There used to be a slight pause before the downswing, but now it is more fluid, which means more precision.
"Most of the serves I put the ball in where I wanted," Alcaraz explained.
"In the first match I struggled a little bit with throwing the ball.
"That helped a lot with the rhythm and what I hit."
Improving his first-serve percentage - which came in at 60% against Nishioka - is the ultimate goal, enabling him to start points with a weapon that opponents find more difficult to return.
As well as accuracy, Alcaraz has added more pace.
His average first serve speed was 190kph at the 2024 Australian Open.
In his opening two matches this year, it has risen to 197kph.
Alcaraz says he does pay close attention to serving statistics - but it isn't all about the numbers.
"It's about feelings. It's about how I hit the ball," he added.
"If I hit it well or not, it doesn't matter. So if I hit the ball really well, and I miss it, it's OK.
"We see the numbers, but not too much."