Returning four-time major winner Kim Clijsters lost in the first round of the WTA tournament in Monterrey, Mexico, just her second match of an ambitious comeback after her 2012 retirement.
The 36-year-old Belgian mother of three played her first match in over seven years in Dubai last month where she was defeated by Garbine Muguruza.
In the first round in Mexico, a still unranked Clijsters was drawn to face second seed Johanna Konta, the British number one, and went down 6-3, 7-5.
"I felt some things were better," Clijsters said in comments carried by wtatennis.com.
"Some things still need a lot of improvement. That's why it's good to play matches. In Dubai, I didn't start well because I was overwhelmed, but today I started and served much better than I did there.
"Those are a few of the positive things, and the points that have to be better, I'll work very hard to improve them for other matches."
Clijsters added: "I've been through different generations and played many players throughout my whole career.
"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 step and improving day by day."
Clijsters turned pro in 1997 and first reached number one in 2003, winning her first major at the 2005 US Open, a feat she repeated - after a first retirement - as an unranked wildcard in 2009 and then in 2010.
Clijsters went on to win a fourth major at the 2011 Australian Open before a second retirement announcement came after the 2012 US Open.
Konta acknowledged she had been star-struck.
"As a young player, I never thought I'd get to play Kim Clijsters in my career," she said.
"I feel truly privileged and honored to share the court with such a champion. It's nice to have her back."