Without Hyeon Chung’s breakout in Milan last November, would the 21-year-old have made South Korean history and reached the Australian Open semi-finals?

Before the Next Gen ATP Finals in Milan, Chung had made only one semi-final in his career (2017 Munich). Winning back-to-back-to-back-to-back matches was not something he did with ease.

Then the Next Gen ATP Finals happened, and everything changed, says Neville Godwin, Chung’s coach since December. In Milan, Chung blitzed through the draw, winning five consecutive matches for the first time in his career.

Sure, the rules were different, but the pressure points were more abundant than ever – deciding duece points, tie-breaks at three-all, and shorter sets that put an even higher premium on service breaks – and Godwin believes Chung’s mindset changed after the 21-and-under tournament.

“I think if you look at his history up until that stage, he hadn’t really gone deep… He hadn’t won many back-to-back big matches. And I think playing in the environment that was in Milan, it was such a great event, and beating really good players… I think really kickstarted him to start believing, ‘OK, I can do this,’” Godwin told ATPWorldTour.com in Delray Beach.

What happened next has been well-documented: Chung came back from two sets to one down to beat World No. 4 Alexander Zverev in the third round of the Australian Open. Chung then knocked out six-time champion Novak Djokovic and Tennys Sandgren of the U.S. to become the first South Korean – male or female – to make the semi-finals of a Grand Slam.

“I really didn’t know I was going to make the semi-finals of a Grand Slam,” said Chung, who had reached the third round of a Slam only once before, 2017 Roland Garros (l. to Nishikori). “I can play more positive in the court and on and off the court, I’m just so happy.”

Chung and Godwin started working together in December, shortly after Godwin had split with South African Kevin Anderson. Chung and Anderson share an agent, so 10 days to a couple weeks after Anderson and Godwin split, Godwin was asked what he thought about working with Chung. They trained for a week together in Bangkok before heading to the ASB Classic in Auckland and the Australian Open.

Godwin, however, has already begun tweaking Chung’s game, and the results have showed. Chung’s power base is his Seqouia-esque legs, so Godwin has brought Chung’s feet closer together before he serves. Think more like an Andy Roddick jumping-straight-up serve, Godwin said.

“He’s obviously got incredibly strong legs so we’re trying to incorporate that more into the serve,” Godwin said. “He’s much more comfortable with it.”

It showed on the blue courts of Melbourne. During the past 52 weeks, Chung has won 71.8 per cent of his first-serve points, and 49.3 per cent of his second-serve points, according to the ATP Stats LEADERBOARDS, powered by Infosys NIA Data.

But in Australia, Chung ticked up both numbers, capturing 72.3 per cent of his first-serve points and almost 53 per cent of his second-serve points.

“I think that was key… his serve numbers definitely went up from where they were last year, which helped him hold serve more… and that frees you up to be more offensive on your return games and that showed as well, because he broke serve many times,” Godwin said.

Godwin has also tried to make Chung more conscious of his routine rally shots. For instance, the South Korean might hit a very clean ball but it lands on the service line, letting his opponent immediately jump on offence.

“That’s a good ball. [But] you don’t want to hit the ball in the middle, you want to hit the ball more away from the guy, so you get the guy moving,” Godwin said. “The more the other guy is moving, now it becomes a moving battle and you move better than anybody, just about, so that favours you.”

The newly-formed team knows it won’t be a straight line at every tournament. There will be dips, early losses, disappointing finishes. But three tournaments in, it’s hard to argue with the changes, the results and the effect Milan had on Chung.

“If he can reproduce what he was doing in Australia, I think he’s very close,” Godwin said of Chung reaching the Top 10. “What remains to be seen, is how often can he reproduce that level of tennis… He’s got a really level head and I think he’s enjoying the process.”

Did You Know?
Chung’s Infosys Serve Rating is 153.7, 10th best on the ATP Stats LEADERBOARDS, powered by Infosys NIA Data.

It’s the hardest hit shot, and is the driving force behind the most common rally length in matches – a rally of just one shot. The serve went in, but the return didn’t come back in play. That rally length happens way more than anything else, right around 30 per cent of total points.

It creates the greatest paradox in our sport – the practice court is overflowing with forehands and backhands, but the rally length that dominates the match court contains only a serve and a return.

See Nadal’s serving patterns in the Infosys Serve & Return Tracker 

An Infosys ATP Beyond The Numbers analysis identifies that only 222 players since 1991 have been able to make their second serve an asset – winning a minimum of 50.1 per cent of second-serve points played.

It’s an astonishing metric since most of us hold the view that the serve in general is a dominant weapon. First serves definitely are, but second serves are absolutely not.

World No. 1 Rafael Nadal is widely recognised as a preeminent returner in our game. He is third best on tour since 1991 in return points won against first serves, and fourth best returning second serves.

But there is a serve category in which he is simply the best: Nadal is No. 1 in second-serve points won, at 57.2 per cent (13,485/23,590). The Top 10 career leaders in this category:

Career Leaders: Top 10 Second-Serve Points Won

When you search farther down the list, just below the 50 per cent win mark, there is an impressive array of players who attained a coveted Top 10 ranking but had a losing record with second-serve points won.

Top 10 Players: Career Second-Serve Points Won

Second serves are the real battleground in our sport. First-serve win percentage is always positive in our sport, all the way down to Under 12s. Not even close with second serves.

At last month’s Australian Open, Nadal averaged hitting his first serve 114 mph (180 km/h) through five matches to the quarter-finals. His average speed on second serves dropped to 95 mph (153 km/h).

That’s a 19 mph (31 km/h) difference, and is the primary reason winning points behind second serves becomes so much tougher. It’s simply not the big hammer like the first serve.