The Kenyan champions had dropped points in the race for the title with a 0-0 draw against Western Stima in the early kick-off in Kisumu.
Batoto ba Mungu had fallen 3-2 to the Brewers when they last faced each other in a top tier game in January, and the visitors were aiming to avenge that loss.
It took the John Baraza-led side just three minutes to get their first goal.
Tusker conceded a free-kick in a promising position and Titus Achesa took it, and the unmarked Ugandan striker Umaru Kasumba rose highest to head the ball past the goalkeeper and get his 16th goal of the season.
In the 20th minute, Boniface Muchiri picked out David Majak in the danger zone, but the latter's well-timed header was cleared off the line by Jacob Faina.
The Tusker custodian made an error in judgement in the 23rd minute, allowing Umaru Kasumba to head the ball back to John Avire, who failed to capitalise on it, skying the ball over the bar.
With about ten minutes left, a seemingly harmless ball from the midfield found its way to the Ugandan, who once again failed to guide the ball on target.
After the break, it took the 2009 KPL champions just two minutes to double their advantage.
Eugene Asike conceded a corner and Asieche took it and the unmarked Brian Magonya headed it into the net to give his team a two-goal advantage.
Justin Ndikumana was forced make to a fine save by Majak, whose curler was destined for the back of the net in the 55th minute.
In the 69th minute, Stephen Waruru raced clear, fooled the defenders before finding Magonya, whose effort was saved by the goalkeeper.
It turned out to be a costly miss for the visitors, as Muchiri halved the defecit in the 85th minute after getting on the end of Sammy Meja's cross.
Former Sofapaka defender Rodgers Aloro then stole a point for the Brewers late into the game after heading in from a corner.