Eighth seed Diego Schwartzman was dumped out of the Grand Prix Hassan II in the first round following a three-set defeat to qualifier Arthur De Greef.
Belgian De Greef came from a set down to claim his first ATP Tour win, saving two match points in the second set as he triumphed 4-6 7-5 6-4 after two hours and 14 minutes in Casablanca.
Sixth seed Andreas Haider-Maurer survived a scare in his opening match, defeating Jan-Lennard Struff 6-2 6-7 (0-7) 7-6 (7-5) in a gruelling affair that lasted over two-and-a-half hours.
Former world number nine Nicolas Almagro continued his comeback from a foot injury with a 6-4 6-1 win over Taro Daniel, while his Spanish compatriot Pablo Andujar overcame Tobias Kamke 6-3 6-4.
Home hope Yassine Idmbarek lost 6-3 6-1 to Mikhail Youzhny but countryman Lamine Ouahab shocked a player ranked 225 places above him by beating world number 88 Robin Haase 6-2 6-4.
Ouahab will now face top seed Guillermo Garcia-Lopez in the second round.
Elsewhere in the draw, Slovenian-born Aljaz Bedene won his first match as a British citizen in three sets against Maximo Gonzalez, while there were also wins for Daniel Gimeno-Traver and Damir Dzumhur.