Dec.22 (GMM) It is now almost certain that Mercedes will head into 2017 with Valtteri Bottas as Lewis Hamilton's new teammate.
Authoritative reports say Felipe Massa has agreed to scrap his retirement plans in order to replace the departing Finn Bottas at Williams.
It is a blow to Pascal Wehrlein, the junior Mercedes driver who had earlier looked the favourite.
"They (Mercedes) were in a very difficult situation," Toro Rosso team boss Franz Tost told the Tiroler Tageszeitung newspaper.
"They have dominated but suddenly lost the world champion, and it happened too late for them to replace him with a top driver because of all the contracts."
So when asked if he would have given the seat to 22-year-old Wehrlein, Tost answered: "Pascal is a great backup driver, but we are talking about the champion team.
"Pascal may be able to fight for victory, but it's too early for him. I've always said that it takes three years for a driver to get comfortable in formula one.
"Of course, Hamilton-Wehrlein was the easiest option for them, but they are fighting for the constructors' championship and a lot of money is at stake.
"And it's also not clear if that driver composition would have a bad influence on the stability of the team," Tost added.
Indeed, Germany's Auto Bild claims that triple world champion Hamilton actually campaigned against Wehrlein joining.
His argument is that the situation of pairing an established champion with a rookie can famously go bad -- just as being Fernando Alonso's teammate at McLaren in 2007 did.
Indeed, it seems boss Toto Wolff was convinced of that possibility, telling the Kolner Express newspaper: "Lewis and Pascal would be an explosive combination.
"What I want to avoid is the Alonso-Hamilton scenario," he added.