Aston Martin have refused to rule out the possibility of Sebastian Vettel making a shock comeback at the season-opening Bahrain Grand Prix.

But he refused to say whether Vettel, who retired at the end of last season, had expressed an interest in being a stand-in.

Stroll has suffered a wrist injury.

Krack said “Plan A” was for Stroll to recover in time for next weekend’s race.

He added: “Plan B we will speak about next week.”

Krack said: “I have had a couple of phone calls with Sebastian but this has been also [the case] last year and will continue in the future.”

Asked whether Vettel had said he was prepared to come back in the event Aston Martin needed a driver to substitute for Stroll, Krack said: “I will not tell you.”

“First our plan is to have Lance in the car and then we continue to see,” he said, adding: “You can ask me five times, we have not made a final decision.”

Stroll is due to try out driving in Aston Martin’s simulator this week in the hope of establishing whether his injury will recover sufficiently for him to compete in Bahrain from Friday.

Vettel called time on his career at the end of 2022 saying he had other priorities, naming spending time with his family and his desire to make an impact on issues of importance to him, especially on social justice and environmentalism.

“Don’t forget one thing – he had a very thorough plan in mind for his retirement and this is something you have to respect,” Krack said. “Let’s see what happens.”

A return for Vettel would be met with huge anticipation not least because it would make him team-mate to Fernando Alonso.

The two are legends who will forever be associated with each other after a long rivalry throughout their careers, including Vettel narrowly beating Alonso to the 2010 and 2012 world titles when they were at Red Bull and Ferrari.

The pair have never been team-mates, and a line-up of the two of them in the same car would heighten interest ahead of the start of the season in Bahrain.

Alonso has joined Aston Martin for this season and produced an eye-catching performance at this week’s pre-season test.

Rivals said Aston Martin’s new car looked like it had moved forward to the head of the midfield, and could perhaps even be the third fastest in the field.

Red Bull appeared on their own out front, but many felt the Aston Martin could be in contention with Mercedes at the head of the midfield.

Krack said: “We need to keep our feet on the ground. Expectations are high and everyone wants to do well this time of year, we are realists and have clear objectives, to improve compared to last year but we will see. The top three teams are very strong.”