Kim Clijsters is back again, eager to see what it feels like to be a professional tennis player at age 38 - two decades after she reached her first grand slam final and one decade after she won her last major singles championship.
The former world No.1 and member of the International Tennis Hall of Fame makes her latest return to the WTA Tour at the Chicago Fall Tennis Classic, which begins Monday.
Clijsters, who received a wildcard, will face Australian Open quarter-finalist Hsieh Su-wei in the first round.
"I have friends back at home in Belgium who said, 'Oh, before I'm 40, I would like to run a marathon' or something like that. And I was like, 'Yeah, so this is kind of my marathon a little bit.' But I enjoy the challenges," Clijsters said during a video conference on Sunday.
"I enjoy when I'm out there and seeing how I react the next day. And like, 'Oh, this thing is reacting this way'. Or my anticipation, 'how can I train to improve that?'
"Things were just so normal back in the day. As long as I feel like I'm still improving, that's what motivates me."
Clijsters, a mother of three who wakes up at 5am at her family's home in New Jersey to train, hasn't competed since a first-round loss at the 2020 US Open.
That was part of a 0-3 record last season after she made a comeback that was interrupted by knee surgery in October and when she got COVID-19 this January.
Those were her first matches since 2012.
Before that, Clijsters originally left the game in 2007, then made her way back in 2009.
She made it to the final of the French Open as a teenager in 2001, part of a 0-4 mark in grand slam title matches before a triumph at the 2005 US Open.
Then came titles at Flushing Meadows in 2009 and 2010 and an Australian Open trophy in 2011.
Clijsters isn't sure how long her latest comeback will last.
That, she said, depends on whether she enjoys the work necessary to remain on tour.
"I've been practising for so long that I'm just super excited to start playing a match and start getting the match routines and the match rhythms, just to teach my brain again how to do that. I've been playing sets in practice, but when it's an official match, it's always a little bit different, anyway," Clijsters said.
"So I'm excited to start that new chapter in my career right now."