The Frenchman had said in Brazil that he expected an announcement to be made at this weekend's Abu Dhabi Grand Prix, with the key choice understood to be whether Marcus Ericsson or Antonio Giovinazzi would took the second seat alongside Charles Leclerc.

But although the team has decided that Ericsson and Leclerc will take part in next week's post-Abu Dhabi Pirelli test, Vasseur said on Friday he was still undecided about the 2018 line-up.

"I was too optimistic," said Vasseur, when asked about his prediction for an announcement this weekend.

"It is just a question of days. I don't think it will happen over the weekend, but probably much more likely next week."

Explaining why a final call had been put back, Vasseur said that the issue was not the most important thing for him, even though it was of most interest to outsiders.

"It is not difficult but it is not the first priority for the team," he explained. "I can understand that it is a key point for you, and probably more for the drivers.

"But it is not a key point for the team and alongside driver choice, we have other topics to discuss. There is a driver position in FP1 and so on. So it will probably take a bit longer than expected."

Alfa Romeo link

Ferrari's closer ties with Sauber have fuelled rumours that part of the discussions could involve the idea of a rebranding of the team's engines as Alfa Romeo.

Vasseur said that such talk was premature for 2018, and that the current talks had not involved such a plan being fast tracked.

"It could be a part of the discussion but so far it is not a topic," he said.

Pushed on whether it was an option for the longer term, Vasseur said: "I am very open."

Giovinazzi still waiting for news

Giovinazzi said he had no choice but to wait for news from Sauber and Ferrari about the Swiss team's plans.

"Like you, I'm waiting as well," he said when asked by Motorsport.com. "Things are happening with Ferrari and Sauber. I don't know yet, I hope to know as soon as possible."

The Italian said he was unconcerned about fellow Ferrari protege Leclerc's name being so strongly associated with a Sauber race seat, irrespective of Ericsson's situation.

"Last year when I was in GP2 my name was in the paddock because I did a fantastic year. I'm not surprised because I know this world. Charles did a good job [in F2], he won the title, so of course now in the paddock Charles is the big name.

"Last year it was my name, this year it's Charles, maybe next year it can be my name. I know this world, and I need just to agree with the voices in the paddock."

Giovinazzi says he has not looked beyond the Sauber chance for 2018.

"Of course it's really late already, we are nearly in December, it's the last race. We'll see. For sure the first thing is to be connected with Ferrari, to work with them, and then we'll see.

"Of course for a driver to be in the car is always better, to compete, the adrenaline in the qualifying and the race, so we need to see if we can first of all see if we can take a seat for next year."