Moroccan side Renaissance Sportive Berkane ended Gor Mahia's perfect Caf Confederation Cup record at home with a 2-0 win in Nairobi on Sunday.
In the absence of star striker Jacques Tuyisenge, veteran Dennis Oliech led Gor Mahia's attack while Joash Onyango partnered Charles Momanyi in defence, since captain Harun Shakava was also suspended.
The chances were limited in the opening minutes with most of the action taking place in the midfield areas. The first chance went the visitors' way in the 15th minute but captain Aziz Mohamed's flick from a free-kick went over the bar.
The visitors got the opener in the 24th minute. Geoffrey Ochieng conceded a free-kick on the right wing, Omar Namsaqui delivered a good ball into the penalty area, and giant defender Issoufou Dayo was well positioned to power home.
Charles Momanyi wasted a huge chance to equalise minutes later, shooting over the bar from inside the area.
Francis Kahata's curled effort was saved by Berkane custodian Abdelaali M'Hamdi, and Boniface Omondi hit the upright shortly after, while M'Hamdi did well to deny Momanyi with a superb save moments earlier.
Gor Mahia keeper Fredrick Odhiambo did well to keep his side in the game three minutes before the break when he denied Barke Helali in a one-on-one situation.
Just before the hour mark, Berkane got a second goal.
Left-back Geoffrey Ochieng was beaten easily on the left flank and after a cross was delivered, the Gor Mahia defenders failed to clear the loose ball allowing Barke El Helali to find the top left corner with his shot.
With the comfortable 2-0 lead, the visitors slowed the game down and frustrated Gor Mahia, who were now in desperate for a goal.
The chances dried up as the clock ticked away and Berkane walked away with a 2-0 advantage ahead of the second leg in Morocco.
Gor Mahia X I: Fredrick Odhiambo, Philemon Otieno, Geoffrey Ochieng, Joash Onyango, Charles Momanyi, Kenneth Muguna, Boniface Omondi, Lawrence Juma, Denis Oliech, Mustafa Francis and Francis Kahata.
Subs : Shaban Odhoji, Wellington Ochieng, Joachim Oluoch, Samuel Onyango, Benard Ondiek, Erisa Ssekisambu and Nicholas Kipkirui.