Sias Ebersohn kicked all of Western Force's points as they ground out a 15-9 win over the Bulls in their Super 15 clash in Perth on Saturday.
Ebersohn's five penalties decided a try-less match as the Force fought back from going 6-0 down to claim their sixth win of the campaign.
The defeat was the Bulls' fourth in a row and meant they returned to South Africa without a single win from their time in Australia and New Zealand.
The former champions have just three wins from 10 matches this season.
They started this clash well enough in testing, rainy conditions, though, as two penalties from Jacques-Louis Potgieter gave them the early advantage.
Ebersohn responded with three of his own as the hosts led 9-6 at the break and they continued to pull clear in the second half, going 15-6 in front.
Bulls' replacement kicker Handre Pollard cut the deficit to six, but the South Africans could not close the gap further as they slipped to another loss.