CHIBA. Japan . May 4 : Unified Korea suffered a double blow while Sweden and Chi nn lightened

I heir grip on the men's singles tournament at the world tennis championships here today, reports AFP.

But it was north of the Korean border where the de feat hit home with two of Pyongyang's top contenders bowing out

Seventh seed LI Oun-Sang. rated one of the best chopper-style strategists in the world, was upset In five sets by China's lowest ranked Individ ual player. Xie Chaojle. In the third round

Then Kim Song-Hui. a fellow northerner competing In Korea's first ever Joint sporting team. lost to China s Wang Tao 3-2 In another third round

Meanwhile the Swedish machine clicked back into gear following shock defeats for their world number two Mikael Appealgren and Eric Undh. the number 12 seed

Jan-Ove Waldner, the world number one. moved effort lessly Into the last 16 with a

21-19. 21-18. 21-11 defeated of Soviet Dimltriy Mazunov.

Waldner. 25. appears on course for a repeat of his 1989 world championships final ■against fellow Swede Jergcn Persson, seeded six.

Persson won the deciding singles in a display of remarkable coolness under pressure

to earn Sweden the world team crown on Tuesday.

The former European champion believes he will go one better here than in Dortmund two years ago and said after beating Germany's Georg-Zsolt Bohm 21-17. 19-21. 21-16. 21-16. In the third round : "My way Is fairly clear to the final. I'm in the kind of shape to win It this time round."

The Chinese and the Koreans may have something to say about that. They each have four players through to the last 16, with China s number one Ma Wenge beating Chinese-born Austrian Ding Yi in straight games to book a place In the fourth round against another former Chinese team player Chen Xinhua, now settled tn England and married with two children.

Chen, who won the team gold with China in Calcutta in 1975 and is now the English number one. eliminated Yugoslavia's Zoran Priorec 21-14. 21-11. 21-18.

South Koreas Olympic champion Yoo Nam-Kyu, seeded fifth here. beat Norwav's Chinese-born star

Wang Yangsheng 21-14. 21-19. 15-21. 24-22.

He is seeded to meet Ma in the quarter-finals and Persson in the semis.

Anrzej Grubba of Poland, seeded third, beat South Korean Kang Hee-Chan to reach the last 16 but made hard work of his 3-2 win.

But another South Korean. Seoul student Lee Cheul-Seung. who had to play through the qualifying rounds to reach the main draw here, pulled off a shock win.

The 17-year-old. who has Just left high school, beat Soviet top player Andrey Mazunov 21-15, 21-14, 21-14 to reach the next round.

Belgrade in 1993

Meanwhile, the sports ruling body confirmed that Mexico had been rejected as the venue for the 1993 World Championships.

Seoul, Beijing and Copenhagen "have shown interest” in replacing them, said International Table Tennis Federation secretary Tony Brooks at the close of the federation's general meeting here which confirmed Belgrade as the venue for the 1995 championship.