Former Portuguese PM tipped to become next UN chief
According to diplomats, none of the five veto powers opposed Guterres' potential appointment in the sixth secret ballot held by the council on Wednesday.
"Today after our sixth straw poll we have a clear favourite and his name is Antonio Guterres," Russia's UN envoy Vitaly Churkin told reporters.
The Portugese politician came out on top in all five previous ballots.
Representatives on the 15-member council were given the chance to cast "encourage," "discourage" or "no opinion" ballots.
Guterres - who presiously served as the UN's refugee chief - received 13 "encourage" votes and just two "no opinion" votes.
The security council will go to a formal vote on Thursday morning.
Following this, the UN's top table will adopt a resolution on their preferred candidate to be presented to the General Assembly.