Nick Kyrgios made a second consecutive early exit as Ruben Bemelmans knocked the third seed out of the European Open on Wednesday.
The world number 20 was stripped of his prize money at the Shanghai Masters and fined $10,000 for unsportsmanlike conduct after quitting midway through his first-round match against Steve Johnson last week, stating that he was struggling with illness and a shoulder injury.
Wildcard entry Kyrgios suffered another blow when he went down 6-7 (3-7) 6-3 6-3 to unheralded Belgian Bemelmans in Antwerp after being given a first-round bye.
The Australian put together an impressive run to the China Open final before losing to Rafael Nadal earlier this month, but was broken twice in the second set and again in the decider to bow out to an opponent ranke 78 places below him.
Julien Benneteau is also through to the quarter-finals after a 6-1 6-1 defeat of Henri Laaksonen, while Joao Sousa ousted Sergiy Stakhovsky 5-7 6-4 6-4 and Steve Darcis reached the last 16 when Cedrik-Marcel Stebe retired after one game of the final set.
Jack Sock ended a five-match losing run stretching back to August by beating Jeremy Chardy to reach the quarter-finals of the Stockholm Open.
The third seed from America had not won since seeing off David Ferrer in Montreal back in August, but overcame Chardy 6-4 6-4.
Sixth seed Fabio Fognini saved a match point in the decisive tie-break before going on to beat Swedish wildcard Elias Ymer 6-4 3-6 7-6 (9-7), while Fernando Verdasco got past Jurgen Zopp to reach the last eight.
Mischa Zverev, Viktor Troicki, Jan-Lennard Struff and Jerzy Janowicz were first-round winners.
At the Kremlin Cup there was a defeat for fourth seed Philipp Kohlschreiber, who went down 6-7 (4-7) 7-6 (7-1) 6-3 against Andrea Seppi.
Third seed Adrian Mannarino saw off qualifier Lukas Rosol 6-3 7-6 (7-4), while Damir Dzumhur and Dudi Sela also moved into the last eight in Moscow. Daniil Medvedev and Mirza Basic made it through to round two.