TOKYO - World No 1 Chen Meng endured a tough contest in the Olympic table tennis women's singles quarterfinals here on Wednesday, being beaten in the first two sets before managing a 4-2 comeback win over Doo Hoi Kem of Hong Kong, China.

27-year-old Chen, runner-up at the 2019 World Championships, rallied to beat 24-year-old Doo 6-11, 6-11, 11-6, 11-9, 11-1, 11-8.

"Once I entered the playing arena, I could feel myself tighten up," said Chen afterwards. "I felt nerves, my body felt a bit heavy."

"I think this is what the coaches have been telling me - at the Olympics, what to expect. I've now truly, fully experienced it," she said.

But Chen, a native of north China's Shandong Province, stayed calm and stern-minded while trailing.

"When I was 2-0 down, although I was quite tight, I was resolute. I took it one point at a time," she said. "At the Olympics, until the final point, anything can happen. As long as I don't give up, I can turn it around."

After winning the third set and tying 9-9 in the fourth, Chen was decisive and scored two straight points to tie the game 2-2, bringing the rhythm of the match on her side.

"It's the right way to go to keep her own rhythm and play as simply as possible," said China's table tennis boss Liu Guoliang from the stands.

In the sixth set, Chen recovered from a blip to regain control of the game with some precise plays, claiming three points in a row to take the set 11-8.

Despite the defeat, Doo, who was the Youth Olympics runner-up seven years ago in Nanjing, has improved her Olympic result from a last 16 finish in Rio 2016 to be among the best eight in Tokyo.

"My matches with her are always exciting. I met her at the World Championships. She knows my game. I've prepared for such difficulties," commented Chen.

For her part, Doo acknowledged her admiration of Chen.

"When I was training with China's national team, I saw her professionalism and spirit. Sometimes at night she would have extra training, working on her fitness," Doo said.

"She's so strong. I knew I had to win on spirit and be really aggressive. I needed to put her in a position where she got nervous, then I would have a little bit of a chance. When she played well, I tried to stand my ground. But my standard is not as high as hers," she added.

Chen will play against Singapore's Yu Mengyu for a spot in the final, after the latter trounced local favorite Kasumi Ishikawa 4-1 earlier on Wednesday.

"Yu has played in more Olympics than me and is older than me. I have no pressure, especially after coming back from the dead, having been 2-0 down today. I hope, starting from my next match, from the very first point, I can take my game to her," Chen said.