The Independent Democrats' Cape Town mayoral candidate Simon Grindrod lost out to the African Christian Democratic Party in the contest for deputy mayor of the city on Wednesday.
The ACDP's Andrew Arnolds won by 105 votes to 104 in the ballot, which followed the election of the Democratic Alliance's Helen Zille as mayor.
The ID voted with the ANC throughout the day's proceedings, in which the tension was almost palpable.
The DA has 90 seats in the 210 member council, the ANC 81, and the ID 23. The remaining seats are held by the ACDP and smaller parties.
In her acceptance speech, Zille said making multi-party democracy succeed in Cape Town would be a huge challenge.
"Our great challenge in Cape Town is to ensure that our diversity is not a weakness but what we claim it to be, our greatest strength," she told her fellow-councillors. "We can make it work."
Speaking in English, Afrikaans and Xhosa, she said the people of Cape Town had chosen a diverse group of parties to lead them. Some would be in government, others in opposition.
"Each role is crucially important," she said.
Multi-party democracy could not succeed if people followed their own one-sided political agendas.
She called on all parties to work together for the good of "this great city" and all its people.
Zille garnered 106 votes compared to ANC candidate Nomaindia Mfeketo's 103. - Sapa