Franziska fought back from 3-1 down to claim a dramatic 10-12, 11-6, 13-15, 7-11, 12-10, 11-8, 11-1 win at OMEGA Sports and Health Center.

His reward is a quarter-final meeting with Dimitrij Ovtcharov, who outlasted 43-year-old Vladimir Samsonov of Belarus in a titanic last 16 clash.

Ovtcharov, the fourth seed, earned a 11-7, 5-11, 11-5, 12-10, 11-7 victory to reach the last eight.

"We are really good friends off the court so it was important to set your mind to that we are now rivals and that it is important to win and put the friendship away for 45 minutes," the German, a four-time Olympic medallist, said. 

"Maybe I did this a little bit better than Vladi. 

"Actually, it was one of my best matches in the past few months so I am very satisfied.

Third seed Timo Boll of Germany is also through after he beat Japan's Yukiya Uda 11-7, 11-6, 11-9, 11-7 on his return to ITTF World Tour action.

In the women's singles draw, top seed Kasumi Ishikawa of Japan sealed a quarter-final berth with an 11-6, 11-4, 10-12, 11-2, 9-11, 11-7 success against China's Liu Xi.

Ishikawa will take on Liu's compatriot He Zhuojia, who defeated Honoka Hashimoto of Japan 14-12, 11-9, 6-11, 13-11, 11-5.

The tournament continues tomorrow.