Belgium's Clijsters was delighted with her comeback performance
Former world number one Kim Clijsters stunned France's Marion Bartoli at the Cincinnati Open in her first competitive match for two years.
The 26-year-old Belgian retired in May 2007 and gave birth to her first child 18 months ago but announced in March that she would return to the sport.
"To win my first match feels good," said Clijsters after her 6-4 6-3 win.
"I surprised myself a little with the way I started and I kept fighting and trying to stay focused. I felt good."
Bartoli, the world number 13, won the Stanford title last week by beating Venus Williams but struggled at the start as Clijsters dropped only five points to race to a 4-0 lead.
The former Wimbledon runner-up fought back to 4-4 but Clijsters still took the set before cruising through the second to set up a second round match against Switzerland's Patty Schnyder.
It was a fine showing by Clijsters who returned to the spotlight in May when she played at Wimbledon alongside Steffi Graf, Andre Agassi and Tim Henman in an exhibition to test the new sliding roof over Centre Court.
Having suffered a series of injuries in the first part of her career, she admitted before this week's emotional return that regaining the necessary level of fitness for top-class tennis had been hard work.
But Bartoli said: "I guess the level of play, yes, it's inside the top 10 already, I can tell you that.
"The way she was moving and hitting, and her physical strength after two years without playing, it's just amazing."
Clijsters, who will also play Toronto before the US Open, has won 34 singles titles, including the 2005 US Open, and topped the world for 19 weeks in total.
Meanwhile, former French Open champion Ana Ivanovic overcame a shocking opening set to overcome American teenager Melanie Oudin 2-6 6-1 6-1 and set up a clash with Hungarian Melinda Czink .
Ninth seed Victoria Azarenka, who has already won three tournaments this year, had few problems in seeing off Estonia's Kaia Kanepi 6-3 7-6.
Ukrainian qualifier Kateryna Bondarenko will play second seed Serena Williams after demolishing Magdalena Rybarikova of Slovakia 6-2 6-2, while world number one Dinara Safina begins her title bid on Tuesday with a second-round meeting with Italian Roberta Vinci.