Nick Kyrgios said after his singles victory on Thursday against Cameron Norrie that he wasn’t pleased with his serving performance. That is a scary thought for the rest of the ATP Cup field.

“I actually thought I served really awful today, to be brutally honest with you. I wasn't feeling my serve at all. It was probably the worst service performance I have had in the Aussie summer by far,” Kyrgios said. “I just felt today I wasn't serving my best. I don't know what it was, but I'm just glad I got the job done.”

Kyrgios leads the inaugural 24-country event in nearly every major service category, and he's won all three of his singles matches.

An astonishing 62 per cent (103/65) of the 24-year-old’s first serves have gone unreturned. That means that for more than six of his 10 first deliveries, he has not had to hit a second shot. He also has led the field in rate of second serves unreturned at 37 per cent (21/57). The next closest player in that category is Yoshihito Nishioka at 28 per cent.

Other service categories Kyrgios leads the ATP Cup in are aces (57) and break points saved (7/8). He is fractionally behind tournament leader Stefanos Tsitsipas in service games won at 97 per cent (36/37). He’s done this all while maintaining a high first-serve percentage, ranking second for the event at 72 per cent.

So although Kyrgios felt he didn’t serve his best against Norrie, who only returned 57 per cent of the Aussie’s first serves and 29 per cent of his second serves, those efforts were plenty to earn recognition from Team Australia captain Lleyton Hewitt.

The former World No. 1 altered his doubles line-up for the deciding match when Australia's tie against Great Britain was level at 1-1, inserting Kyrgios and Alex de Minaur in place of Chris Guccione and John Peers.

“I couldn't really afford to have him sitting on the sidelines with how well he served in the singles,” Hewitt said of Kyrgios.

So if Kyrgios feels he can raise his serving level even higher, that will pose difficult questions for Team Spain or Team Belgium.