Kim Clijsters remains in search of a first win in her comeback to the sport after falling in the first round of the WTA Monterrey tournament to Johanna Konta.
Konta, the second seed at the Mexican event, beat Clijsters 6-3 7-5 to take her place in the second round, where she will face Tatjana Maria.
Clijsters most recently retired in 2012 before embarking on a comeback at the Dubai Tennis Championships a fortnight ago.
There, she fell to the in-form Garbine Muguruza 6-2 7-6(6).
Monterrey proved an extremely similar scenario; Clijsters again drew a top-20 opponent and showed glimpses of her best in the second set, yet was ultimately weighed down by her unforced errors and erratic serving.
The Belgian will head to next week’s tournament at Indian Wells as a wildcard seeking her first victory, which is more likely given she will play an unseeded opponent. All 32 seeds at Indian Wells receive a first-round bye.
Konta was also seeking a first win in season 2020 after losing her first three matches.
The Brit was brilliant in 2019, hauling her ranking up from No.47 in early May to No.11 by September after a French Open semifinal run plus quarterfinal finishes at Wimbledon and the US Open.
Yet she did not play for the rest of 2019 after the US Open as she dealt with a knee injury.
She initially found it difficult to recapture that form and momentum on her return but looked assured against Clijsters on Tuesday night, playing with controlled aggression and successfully moving the Belgian around the back of the court.
She also served with authority, landing 83 per cent of her first serves, winning 80 per cent of those points, and not allowing Clijsters a single break point.
"Quite frankly, as a young player I never thought that I'd get to play Kim Clijsters in my career, so I feel truly privilege and honoured to share the court with such a champion. It's nice to have her back,” Konta said on court.
"She's an incredible ball-striker; her ability to do things with the ball is what made her a multiple Grand Slam champion and it's why she's able to come back – second match back after seven years, I think – and to be playing at a level like that, I mean, that's not exactly every day, that's for sure.
"Very pleased to have come through a tough match. Really happy with my performance to … go into the second round.
"A lot of really special things tonight.”
It was less special for Clijsters, who midway through the second set had already sprayed 30 unforced errors.
But the naturally ebullient Clijsters was able to see the positives that came out of the match, which lasted one hour and 25 minutes.
“In Dubai, I didn't start well because I was overwhelmed, but today I started and served much better than I did there,” Clijsters said.
“That's why it's good to play matches.
"Some things still need a lot of improvement. The points that have to be better, I'll work very hard to improve them for other matches.
“I'm still at a stage where I want to focus on what I'm doing and how I'm feeling, and also start reading my opponents. It's a process that I have to trust and keep working hard to improve in every match I play.
“I'd like to take big steps but I have to focus on small steps and improving day by day."
Earlier on Tuesday, seventh seed Azarenka – a finalist in Monterrey last year – was shown the door in just 67 minutes by Slovene Tamara Zidansek.
It was Azarenka’s first match since last year’s US Open and her rust showed, with the Belarusian losing 6-2 6-2 to the world No.74.
Joining Konta and Zidansek in the second round was No.1 seed Elina Svitolina, who got past Danka Kovinic 6-3 6-2 to snap a three-match losing streak.