Helmut Marko has reacted furiously to claims from reserve driver Pierre Gasly that he will replace Daniil Kvyat for the Singapore Grand Prix.
Kvyat has endured a dismal season to date, losing his seat at Red Bull to Max Verstappen after just four races of 2016 and subsequently struggling to challenge new team-mate Carlos Sainz Jr in the sister car.
Frenchman Gasly is the current championship leader in GP2 - which runs concurrently to selected Formula One events - but the junior formula does not race at the Marina Bay Circuit.
Gasly was quoted by Movistar: "They told me: 'Yes, you will race in Singapore'. I hope this is true, but at the end, I have to see Helmut [Marko].
"I know he [Marko] hopes I will be the best in GP2, and that is what I am trying to do right now. I think things are going well in the last races, so let's see."
Marko heads up Red Bull's development programme - with drivers generally passing through Toro Rosso before racing for the four-time constructors' champions - and the Austrian did not hold back when quizzed on Gasly's claim by Sky Sports.
"Who said that? It's absolute rubbish," he snapped. "Kvyat will have his chance to recover and we won't make any decisions before mid-October who will have the seat next year in Toro Rosso.
"It's news to me and, believe me, I will be on the phone to him [Gasly] immediately."
Kvyat was also bullish when quizzed on his thoughts on a possible second demotion of a miserable 2016.
"I don't really care about these rumours," he said. "I'm just doing my job, whatever they decide they decide."