Grigor Dimitrov crashed out of the Stockholm Open to the unseeded Jiri Lehecka in a three-set thriller on Tuesday, as Botic van de Zandschulp also fell at the first hurdle at the European Open.

Dimitrov, seeded sixth in the Swedish capital, came up short against Lehecka, who seized a surprise 6-4 1-6 7-6 (7-5) win, his first on the ATP Tour since July.

Victory for Alex de Minaur was far more predictable, a 150th at tour level coming courtesy of a straight-sets defeat of Benjamin Bonzi.

In Antwerp, Dominic Stricker handed Van de Zandschulp a swift exit, winning 6-2 6-4 to stay on Lehecka's coat tails in pursuit of a place at the Next Gen ATP Finals.

Stricker's reward for this win will be a second-round encounter with French veteran Richard Gasquet, who knocked out three-time grand slam champion Stan Wawrinka on Monday.

At the Napoli Cup, fifth seed Miomir Kecmanovic saw off wildcard Flavio Cobolli with ease, but others found life rather tougher.

Respective seventh and eighth seeds Albert Ramos-Vinolas and Adrian Mannarino fell to Nuno Borges and Pedro Cachin.