Magda Linette was the highest-profile casualty at the Transylvania Open on Wednesday after suffering a straight-sets defeat against Xinyu Wang.
Four of the seeded players have now fallen at the first hurdle in Cluj, with Lucia Bronzetti also joining Linette, Ana Bogdan and Marta Kostyuk in suffering early exits.
Fifth seed Linette was beaten 6-2 6-4 by Wang, while ninth seed Bronzetti went down 4-6 6-2 6-4 against world number 89 Dalma Galfi.
Anna Bondar is through to the quarter-finals, though, with the eighth seed enjoying a 7-6 (7-3) 6-4 victory over Harriet Dart.
Jasmine Paolini took just 58 minutes to wrap up a resounding 6-4 6-1 win over Dayana Yastremska.
Next up for the Italian is a last-eight showdown with Wimbledon quarter-finalist Jule Niemeier, who overcame Kamilla Rakhimova 6-4 6-4.