Venus Williams of the United States returns a shot to Marta Domachowska of Poland during their quarter-final match of the Hansol Korea Open tennis tournament at Olympics Park in Seoul, South Korea, yesterday. Williams won 6-2, 6-3. - AP Photo/Ahn Young-joon

SEOUL, South Korea (AP)

Venus Williams reached the Korea Open semi-finals yesteray by beating Marta Domachowska of Poland 6-2, 6-3.

The top-seeded Williams used powerful and accurate returns but still trailed 3-1 in the second set before winning five straight games.

"I wasn't at my best today," the Wimbledon champion said. "There is no specific problem, I just feel a little tired. Now it is time to get ready for the semi-final tomorrow."

Williams will face Flavia Pennetta in the semi-finals. The Italian defeated Ayumi Morita of Japan 6-1, 6-2.

Second-seeded Agnes Szavay of Hungary retired with an injury after splitting the first two sets with Eleni Daniilidou 4-6, 7-5.

The fifth-seeded Greek will next play fourth-seeded Maria Kirilenko, who beat Catalina Castano of Colombia 6-3, 6-0.