Marcos Baghdatis dumped top seed David Ferrer out of the Aegon Open in straight sets on Tuesday.
Ferrer had spoken ahead of the tournament about its importance, suggesting it was more than just a chance to warm up for Wimbledon.
However, the Spaniard's preparations for the grass-court grand slam, which starts next week, were dealt a blow as Baghdatis prevailed 6-2 7-6 (7-4) in the second-round meeting.
A one-sided opening set was dominated by the Cypriot, who broke twice, but Ferrer proved more resilient in the second, forcing a tie-break.
Ferrer's hopes of taking the match the distance were scuppered by a couple of mini breaks as Baghdatis secured a third-round match against Alexander Zverev.
Beaten Aegon Championships semi-finalist Viktor Troicki was also defeated, the sixth seed succumbing 6-4 6-2 to Sergiy Stakhovsky.
Troicki was impressive in his run to the last four at Queen's Club, where he was beaten by eventual winner Andy Murray, but had no answer to an impressive display from his Ukrainian opponent.
Second seed Gilles Simon was given a scare against Marcel Granollers, the Frenchman battling back from a set down to win 4-6 7-6 (7-3) 7-6 (7-0).
Juan Monaco, Martin Klizan and Thomasz Bellucci were also among the seeds to fall, losing to Denis Istomin, Simone Bolelli and Alexander Zverev respectively.
Leonardo Mayer was a comfortable 6-3 6-1 winner against Hyeon Chung, while Pablo Cuevas overcame Dudi Sela 7-5 6-4. Seeds Dominic Thiem, Adrian Mannarino and Sam Querrey also secured safe passage, with Malek Jaziri, Aljaz Bedene and Santiago Giraldo all dismissed in straight sets.
A quartet of players were forced to play twice after Monday's rain delays, their double shifts providing mixed results.
American Tim Smyczek was beaten at the second attempt by Jiri Vesely, having overcome home hope James Ward, while Thomas Fritz lost at the hands of Feliciano Lopez.
However, Lu Yen-Hsun completed back-to-back wins over Ruben Bemelmans and Andreas Seppi. Joao Sousa dumped out Sam Groth, who earlier in the day defeated Mischa Zverev.
