And to think, this is just day one. Here are the top four biggest upsets of the day, rated on a shock scale between 1 and 10.

The player: Cristian Pletea, Romania, men’s singles 

The upset: Pletea ejected top seed Tomokazu Harimoto of Japan, the adolescent genius who won the 2017 Czech Open at just 14, in what he himself described as the biggest win of his career. The talented Romanian, just 19, has plenty to boast about before — he won the Europe Youth Top 10 for the past two years and has shown that he’s one of the few European players who can keep up with the speedy pace set by the Chinese and Japanese. Still, nobody quite expected Harimoto to go out in the round of 32.

Shock factor: 9.8.

The players: Stephanie Loeuillette and Audrey Zarif, France, women’s doubles

The upset: Loeuillette and Zarif unexpectedly ended China’s Chen Xingtong and Qian Tianyi quest for the final in four fiercely played games (13-15, 11-9, 11-9, 12-10) decided by sharp rallies that favoured the French. It’s a boon for the 27-year-old Loeuillette and 21-year-old Zarif, which should fill them with confidence heading forward.

Shock factor: 8.0.

The players: Ma Te and Wu Yang, China, mixed doubles

The upset: No. 1 seeded Lee Sangsu and Jeon Jihee of Korea were the other top seeds to fall on the opening day of main draw play in Olomouc, capitulating to China’s Ma Te and Wu Yang 3-2 (6-11, 11-6, 11-6, 10-12, 13-11). The Koreans may have been the no. 1 seed, but China is never to be counted out, even when the pair doesn’t practice together often, as Ma and Wu admitted afterward. Ma, by the way, is causing upsets right and left — late in the day, he eliminated Hong Kong’s Wong Chun Ting, setting off a tiny aftershock to the earthquake caused by Harimoto’s early exit.

Shock factor: 6.5. 

The player: Sofia Polcanova, Austria, women’s singles

The upset: This is less an upset than a back-from-the-brink encounter, but we’ll count it anyway. Polcanova, down 0-3 against Chinese Taipei’s Chen Szu-Yu, was able to turn the tables on Chen to win 4-3, with both players into the double digits in the fifth and sixth game (7-11, 9-11, 6-11, 11-6, 13-11, 12-10, 11-8).

Shock factor: 5.0.