The Sugar Millers were on 46 points, level with Tusker, and a win was needed to get past the Brewers.
For Sharks, maximum points could have taken them to the eighth position with 41 points.
It took the hosts just two minutes to score the opener courtesy of Solomon Omollo, who did well to get past the napping defenders.
Neither of the two teams could get another goal in the first half, although Enock Agwanda came closest but failed to hit the target.
With about five minutes remaining, the striker managed to capitalse on Brian Bwire's mistake to double the advantage.
For Sharks, this is their eighth loss this season.