USIU Martials handed Mean Machine its first defeat of the season after edging the university of Nairobi side 19-12 in a KRU Championship round nine tie on Saturday 10 February in Nairobi.
Skipper Junior Onyango and his understudy Aggrey Oguna both inked their names on the score sheet.
The lose Means that Machine relinquish top spot to Menengai Oilers who handed Egerton Wasps a 19-8 hiding in Njoro.
In Eldoret, Western Bulls scored three tries and a single conversion to see off Moi Arsonists 17-10.
The hosts scored through a three pointer and a penalty try that was awarded to them after a Bulls infringement.
In other matches,Catholic Monks overcame South Coast Pirates with a 21-10 score as JKUAT Cougars lost to Ngong Warriors 29-10 at the Kibiko Secondary.