MediaCom and ZenithOptimedia will go head to head for the business, which is worth £15m.
The decision means incumbent Vizeum has lost the business after 20 years. MindShare has also been knocked out of the process.
An appointment is expected to be made at the end of November.
Molson Coors (UK) is part of the world's largest global family brewer, whose brands include Carling, Grolsch and Coors Light. The company has a strong reputation for building brands.
Nicola Young, director of marketing (insight and communications) at Molson Coors, said: ‘This has been an extremely difficult decision for us. We have had Vizeum as a key strategic partner for over 20 years and it has successfully worked alongside us across all of our brands.'
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