Melvin Tan has been a fan of Roger Federer since 2001, but he found himself rooting for the Swiss great's Australian Open first-round opponent Denis Istomin last week.

The only Singaporean in the Yonex racket-stringing team at the first Grand Slam of the year got his first assignment upon his arrival in Melbourne on Jan 7 - and it was Istomin's racket.

"When I found out he was playing against Federer, I thought, 'Oh no, what's going to happen?'. But of course I stayed professional and committed to stringing his racket," Tan told The Sunday Times on Thursday. "As I followed the match, I ended up supporting Istomin."

He has been stringing rackets since he was 16 and this is his first Grand Slam assignment.

The 42-year-old was not due to start work on the day he arrived, but the team needed "immediate reinforcement" so he dropped his luggage at his service apartment and headed straight to Melbourne Park.

"The rackets were being checked in fast and furious by players during the qualifying rounds. And 25 rackets later, I finally ended my first day and hit the bed at 2.30am," said Tan, who strung more than 200 rackets in eight days.

"I felt fortunate to represent our country and I felt proud stringing every single racket. Every job I had, I gave my 100 per cent. It didn't matter whether it was the racket of a qualifier or a top-ranked player."

He also strung rackets for former women's world No. 1 Kim Clijsters, who partnered 2014 Australian Open champion Li Na for the legends doubles tournament, and Greek Stefanos Tsitsipas, who defeated Federer in the fourth round.

He quipped: "I did not string his (Tsitsipas') rackets for the match against Federer, so I am not to be blamed for his defeat!"

To prepare for the job, he worked out more regularly.

From exercising once a week, he started playing tennis at least thrice and going to the gym every morning.

"I knew I had to be fit because of the long hours on my feet with a lot of movement in my fingers and arms," said Tan, who owns a sports shop in Far East Shopping Centre.

His hard work paid off. Even though he had only four to five hours of sleep daily, Tan did not feel tired stringing more than 20 rackets for about 17 hours every day.

The most stressful part of the job was when he had to string for players while they were playing.

He said: "Some players needed a change in racket tension because of weather conditions. So I had to do it really fast in 12 minutes when normally I take about 20 minutes."

Besides aiming to return to Melbourne next year, he also wants to string at a Masters 1000 event (which ranks below the four Slams and season-ending ATP Finals) in the United States or Europe.

He added: "I hope this opens up doors for me and other Singaporeans to string at events."