But world champion Chen ensured normal service resumed again as she topped the score sheets with 392.35 ahead of tomorrow morning's semi-final.
Malaysia's Pandelela Rinong Pamg was her nearest rival, some 43.35 points behind, but Chen still found reason to be disappointed.
'I feel it's all right. Two dives, I feel, were not really under control - the second and the fourth,' she said.
'Before every dive the whole routine goes through my mind.'
Germany's Christin Steuer, a last-minute inclusion for injured team-mate Nora Subschinski, was third ahead of Australians Brittany Broben and Melissa Wu.
'I found out yesterday lunchtime I was competing,' Steuer said.
'I was the reserve, and when Nora wasn't getting better, I just jumped in.
'I got third place, so that's good. I didn't see the competition, I didn't even see my own dives. I was surprised to reach third position.'
Australia's 16-year-old hopeful Broben said: 'I could have dived a lot better tonight but I'm hoping to save it for the final.
'It doesn't feel like the Olympics but when I saw the big London 2012 on the bottom of the pool, that's when it hit me.
'I suppose I would like to get a medal but there are a lot of strong competitors so I haven't really thought about it.'