The most notable casualty in this ITTF World Tour event was Japan's Koki Niwa, the number three seed, who was defeated 13-11, 11-6, 11-1, 11-9 by Portugal's Marcos Freitas.

South Korea's Lee Sangsu also suffered a surprise early exit.

The number five seed was beaten 11-6, 11-13, 11-7, 11-5, 10-12, 9-11, 11-6 by Slovenia's Darko Jorgic.

Vladimir Samsonov, the number eight seed from Belarus, also fell after being defeated 11-9, 8-11, 11-8, 11-9, 15-13 by Japan's Yuta Tanaka. 

But the number one seed, Japan's Tomokazu Harimoto, cruised into the second round with an 11-7, 11-9, 14-12, 11-6 victory over China’s Zhu Linfeng. 

Zhao Zihao emerged the only Chinese player to progress to round two.

He beat France's Simon Gauzy, the number 12 seed, 11-9, 9-11, 11-6, 11-4, 4-11, 11-4.

In fact, so many seeds were defeated in this opening round that by the end of it the qualifiers outnumbered the seeds.

There were also upsets in the women's tournament, although at the lower end of the rankings.

Austria’s Sofia Polcanova, the number 10 seed, was defeated 13-11, 11-5, 11-9, 12-10 by China's Mu Zi, who does have pedigree having won a bronze medal at the 2015 ITTF World Championships. 

Japan’s Kasumi Ishikawa, twice a previous winner in Panagyurishte, made a most imposing start.

She beat Portugal’s Shao Jieni 11-6, 11-6, 11-6, 11-6.