Ellis Asieche sent Mathare in front with a well-taken goal in the 10th minute, sending the home fans into a frenzy.
They hope the two additions will help them wrestle the KPL title from Gor Mahia
The sides drew 1-1 at Ruaraka Grounds on Saturday to remain in contention.
The trophy tour is a celebration, allowing supporters to see the biggest prize in global club football.
The arrival of the Croatian signals a renewed hope that the club can once again ascend to the pinnacle of Kenyan football.
Team manager Gilbert Ledama confirmed the acquisition of left-back Steve Otieno from Kisumu All Stars
Kiriago, a second-year student, won the 10000m and 3000m titles and finished second in the 5000m race.
The Tanzanian side had struck a deal with K’Ogalo to have Onyango cross the border, but the deal never materialised.
The brewers have hit their stride in the second leg of the season, stringing together three consecutive wins.