Bandari had lost just once in the league, to Kakamega Homeboyz who beat them 4-0 at the Bukhungu Stadium on January 30.
The mid-week defeat was the third for coach Bernard Mwalala since he moved to Mombasa from Nzoia Sugar. Solomon Omollo put Sony Sugar into the lead just two minutes after the break before Derrick Otonga doubled the scores in the 71st minute for a deserved win.
The shock defeat denied Bandari a chance to reclaim the leadership of the table. The Dockers remained third on the log with 32 points, one less than leaders Sofapaka. Sony Sugar meanwhile moved joint fifth with Kariobangi Sharks, both on 29 points.
Elsewhere, Tusker and Ulinzi Stars settled for a point each following a 1-1 draw at the Ruaraka Ground. Enosh Ochieng scored early in the second half to cancel out Sydney Ochieng’s 34th minute lead for the Brewers.