Ito, the world number three, recovered from a poor start to overcome Sato 9-11, 7-11, 11-6, 11-8, 11-1, 11-2 at Budapest Olympic Hall.

The Japanese player's opponent in the last four will be Han Ying of Germany, who upset Japan's Miu Hirano with a battling seven-game victory.

Miu, the fourth seed, moved to the brink of a place in the semi-finals when she led 3-2 but contrived to lose the last two games and fell to a surprise 4-11, 11-9, 11-9, 9-11, 8-11, 11-5, 11-9 defeat.

"I had the tactics right from the start but during the match I found the better way too," Han said.

"Last game I changed the directions of play to her forehand side and it paid off. 

"At the match point all I was focusing just to get one more ball on the table then her."

Cheng I-Ching of Chinese Taipei and Japan's Kasumi Ishikawa will meet in the other semi-final in the women's singles event.

Cheng defeated Doo Hoi Kem of Hong Kong 11-7, 11-5, 11-6, 11-8, while second seed Ishikawa beat Nina Mittelham of Germany 11-3, 11-6, 11-3, 11-7.

In the men's singles, top seed Tomokazu Harimoto ousted Germany's Benedikt Duda 12-10, 9-11, 11-6, 12-10, 9-11, 11-4 to qualify for the last four.

Yukiya Uda of Japan booked his place in his first World Tour semi-final after beating Austria's Robert Gardos 11-6, 7-11, 16-18, 11-7, 11-6, 11-7.