By ESPNSTAR.com staff
Gombak, who were up against foreign side Harimau Muda B in their opening round match at the Jurong West Stadium, took the lead after just 11 minutes when Christopher Anderson fired them in front.
Watch: Highlights: Gombak 3-0 Harimau Muda.. More Videos
Fairoz Hasan then doubled the Bulls' lead in the 53rd minute before K. Vikraman wrapped things up when he grabbed a third nine minutes from time.
Up next for Gombak will be a quarter-final clash with Hougang, who beat Tanjong Pagar United 4-3 on penalties after the game had ended 1-1 after 120 minutes.
After a goalless first half at the Queenstown Stadium, the Cheetahs went ahead when Mamadou Diallo found the back of the net nine minutes after the break.
However, the Jaguars hit back through Hafiz Osman in the 70th minute and with neither side being able to find the winner, the game went to penalties.
With the score at 3-3 after misses by Hougang's Ignatius Ang and Tanjong Pagar's Jonathan Xu, Stanislav Vidakovic netted his attempt to put the Cheetahs in front before Jang In-jun missed his attempt, sending the Jaguars out in the process.
Sunday's RHB Singapore Cup Results
Gombak United 3-0 Harimau Muda B
Tanjong Pagar United 1-1 Hougang United (3-4 on penalties)