Rwandan striker Jacques Tuyisenge fired K’Ogalo into the lead but ended up paying the prize after he was stretched off the pitch with what looked like a nasty knee injury.
Zoo contained the defending champions until the 40th minute when Tuyisenge announced his return to Gor Mahia squad with an opening goal after slotting home from Boniface Omondi’s assist.
Tuyisenge, who sat out of Gor Mahia’s 2-0 win over Leones Vegetarianos in a Caf Champions League clash last Saturday, was replaced by George ‘Blackberry’ Odhiambo.
Bernard Ondiek also picked a knock from a dangerous tackle and the injuries may prove critical for coach Dylan Kerr ahead of next week’s return leg match away in Equatorial Guinea.
Zoo survived K’Ogalo’s scare in the first 12th minutes following a barrage of attacks after the league champions won the first corner in the 11th minute.
K’Ogalo extended their advantage just two minutes after resumption after Omondi tapped in from close range. Gor Mahia's lead, however, lasted only for eight minutes after Zoo pulled one back through Johnstone Ligare in the 56th minute.
Samwel Onyango pounces on a rebound after Kagere had sent a powerful shot to add to Joachim Oluoch’s third goal and a comfortable win for Gor Mahia.
Zoo Kericho starting XI: Martin Elungat, Johnstone Ligare, Stanlaus Akiya, Isaac Kipyegon, Gifeon Kibet, Dennis Otieno Geoffrey Gichana, Michael Madoya, Danson Namasaka, Nicholas Kipkirui and Bernard Odhiambo.
Subs: Samuel Koko, Dominic Ouma, Sabiri Sindani, Kepha Ondati, Ernest Kipkoech, Martin Oile, Derrick Anami and Dominic Kiprono.
Gor Mahia starting XI: Shaban Odhonji (GK) 7. Bernard Ondiek 11. Boniface Omondi 10. Cercidy Okeyo 27. Charles Momanyi 18. Harun Shakava (Cpt) 9. Jacques Tuyisenge 15. Johachim Oluoch 22. Meddie Kagere 26. Philemon Otieno and 21. Wesley Onguso.
Subs: 23. Bonface Oluoch 8. Francis Kahata 25. George Odhiambo 14. Innocent Wafula 24. Lawrence Juma 6. Samuel Onyango and 3. Welington Ochieng'.