Aruna Quadri of Nigeria returns the ball against Timo Boll of Germany during a men's singles round 4 table tennis match at the 2016 Rio Olympic Games in Rio de Janeiro, Brazil, on Aug. 8, 2016. [Photo/Xinhua]

"He was leading 3-0 and I found better tactics to turn it 2-3, leading also in the sixth set. But he was risking a lot and he deserved to win because he played really fantastic," added Boll.

The German star paddler has been the second big-name victim under Aruna's racket after the world No. 40 made a brief through into the last 16 by beating the fifth seed Chuang Chih-Yuan of Chinese Taipei in straight sets.

Named the world table tennis governing body ITTF's Player of the Year in 2014, Aruna, who trains in Belgium, once made troubles to then world No. 1 Zhang Jike in the 2014 World Cup quarterfinals.

"The whole rhythm is different against him because he has a very strong forehand and weaker backhand, but his backhand is in a totally different rhythm, coming slow and forehand coming quite fast.

"So it's difficult to get used to it," commented Boll. "He's moving so well, and also tactically smart."

The Nigerian, however, told a post-match mixed zone that he just could not understand the ball' s rotation when it comes to force a backhand.

"It's really more difficult to play backhand. I can't understand where the ball will come with the rotations," he said.

The birthday boy will face world champion and the top seed here Ma Long of China on Tuesday in the Olympic quarterfinals.