Daniel Ricciardo thinks it is unlikely that Red Bull will race Renault's updated engine at the United States Grand Prix.
Renault has used 11 of its 12 development tokens to introduce a raft of updates to lift the performance of its power unit.
However, with Ricciardo sceptical that the changes have delivered much of a horsepower boost, he reckons it will not be worth taking a grid penalty to race it.
"It's available if we want to use it – that will mean a penalty though," he said. "So we have to understand if it is worth it.
"It [the gain] is not massive, from my understanding, so it is probably not worth taking it. I think we are down such a chunk that I don't think we will gain enough initial time to make it up.
"So if we start from the back, I don't think we will make the ground up we need. Right now we are less likely to take it – but hopefully today they will tell me something different and they have found a big chunk of horsepower."
The Renault update situation comes amid ongoing uncertainty about the future of Red Bull, as it chases an engine deal for next year.
Ricciardo said that he was optimistic a solution would be found to keep the team on the grid, but said the bigger issue for him was on if the engine it had would be competitive enough.
"Not much has changed," he said. "We have still not really confirmed anything yet, but from our side I am confident we will be racing, and confident we will be there. And hopefully competitive, that is more the concern.
"I am confident we will be on the grid, the concern is, can we be competitive? I believe we can.
"This year we have a couple of podiums which is nice, but we want to be competitive again and that is as important as being on the grid."