Red Bull team boss Christian Horner believes Daniel Ricciardo's decision to switch to Renault next year was partly influenced by the growing strength of current teammate Max Verstappen.
Ricciardo announced last week that he would leave Red Bull and drive for Renault next year after signing a two-year contract with the French manufacturer. In terms of outright competitiveness, the move represents a step backwards for Ricciardo, with Renault unlikely to eliminate the significant gap in performance to Red Bull in the short-term.