(CNN) -- Kim Clijsters saw her comeback run ended by world number one Dinara Safina in the quarterfinals of the WTA tournament in Cincinnati.
Clijsters came up short against an inspired Safina in Cincinnati.
Unseeded Clijsters, returning to action after a two-year absence, ran out of steam against the Russian, who won 6-2 7-5.
It was a commanding performance from Safina, who will increase her advantage at the top of the world rankings with the defeat of world number two Serena Williams in the previous round.
Former world number one Clijsters, who had beaten Safina in six of their seven previous meetings, was impressed by her opponent.
"Dinara played some of the best tennis I've ever seen her play. It was by far the best she has played against me," Clijsters told the official WTA Tour Web site www.sonyericssonwtatour.com.
The Belgian said she had been satisfied by her first competitive appearance after getting married and giving birth to her first child.
"I'm definitely pleased with the level I had in these four matches. Looking back today, maybe I should have tried a few different things. But overall, I'm happy and satisfied with how everything has been."
Safina next plays in-form Flavia Pennetta of Italy in the semifinals of the $2 million hardcourt tournament.
Penetta, bidding for back to back titles, saw off Slovakian Daniela Hantuchova, 6-3 6-3 and will become the first Italian woman to reach the world top 10 when the new rankings are released.
The second semifinal on Saturday will feature Elena Dementieva of Russia and Serbian Jelena Jankovic.
Dementieva beat Danish eighth seed Caroline Wozniacki, 6-2 6-1 and fifth seed Jankovic thrashed Sybille Bammer of Austria, 6-0 6-3.