Konta, who prevailed 4-6 6-4 6-3, needed two hours and eight minutes to quell the challenge of her American opponent as her usually reliable serve sputtered early on before eventually coming to her rescue at the Pat Rafter Arena.

“This was my first match in quite a while, so I’m really happy to have had such a competitive match against such a great player,” she said.

“It was a really tough first round for both of us. Madison is an incredibly good player, so I feel very lucky that I got to play her so early on and really have a good match. She has a big game so when my chances came I had to take them.”

World No19 Keys missed eight opportunities to break Konta’s serve before she finally succeeded while up 5-4 to take the first set with a powerful forehand drive.

Konta appeared to calm her serve and nerve in the second set, fighting back with an early break to go up 3-2. The world No9 then held on to level the match at one set apiece.

The Briton battled her way to a 2-0 lead in the decider as Keys began to tire and finished the match with another break to set up a clash with Ajla Tomljanovic in the next round.

Belarusian qualifier Aliaksandra Sasnovich came from behind to upset sixth seed Kristina Mladenovic 1-6, 6-3, 7-5 while Elina Svitolina beat Spain’s Carla Suarez Navarro 6-2, 6-4. Ukraine’s Lesia Tsurenko then stunned eighth seed Ashleigh Barty 6-3, 6-2.

Double Wimbledon champion Petra Kvitova withdrew from the event with a viral illness. The 27-year-old Czech was unable to take the court against Anett Kontaveit and was replaced in the draw by lucky loser Heather Watson.

After losing the opening eight games Watson was never in the match, with the Estonian wrapping up victory for the loss of just three games.

In the men’s draw, Mischa Zverev powered past Australian qualifier John-Patrick Smith 6-4, 7-5 while local hope Matthew Ebden dumped out Frances Tiafoe with a 6-3, 6-2 victory that sets up an all-Australian second-round clash with the big-serving Nick Kyrgios.

In Shenzen, world No1 Simona Halep swatted aside American Nicole Gibbs while Maria Sharapova was flawless in her straight-sets victory over Romania’s Mihaela Buzarnescu.

Halep, who sealed a 6-4 6-1 victory, struck three aces and fired 12 winners and was at her aggressive best to set up a second-round clash with China’s Duan Yingying, who defeated Evgeniya Rodina 6-2 7-5.

Sharapova hit 18 winners and needed an hour and 22 minutes to despatch the seasoned Buzarnescu 6-3, 6-0 for a winning start to the year.

Men’s No1 Rafa Nadal, who is struggling to get any match practice before the Australian Open, will play an exhibition event at Melbourne Park in the week leading up to the season-opening Grand Slam.

The 31-year-old Spaniard has not played since he withdrew from the season-ending World Tour Finals in London in November with a knee injury.

He had already withdrawn from an exhibition tournament in Abu Dhabi, this week’s Brisbane International and another event in Sydney, citing a lack of time to properly prepare.

However, the 16-times Grand Slam winner will be part of the winner-takes all Tie Break Tens event at Melbourne Park on Jan. 10, five days before the Australian Open begins.

The eight-man field also includes Novak Djokovic, Stan Wawrinka, Nick Kyrgios, and former world No1 Lleyton Hewitt.