Although Toto Wolff concedes that Lewis Hamilton has a "higher" chance of winning the World title than Valtteri Bottas, Mercedes won't commit to making Hamilton number one.
Having claimed his third successive win in Singapore on Sunday, Hamilton moved 28 points clear of Sebastian Vettel in the race for the Drivers' title.
His P1 also put more distance between himself and Bottas, who remains third, 51 points behind his team-mate.
And although Wolff acknowledges that the numbers mean Hamilton does have a better chance of winning the title, he says Mercedes won't openly back him as their number one drivers.
"I think that it's pretty obvious that his chance of winning the Drivers' Championship is higher than Valtteri's," the Mercedes motorsport boss explained.
"So like we've done in the past we will look at the preceding race and assess it, then the decision becomes obvious.
"I wouldn't want to give a straight commitment and say he's our number one because I don't want to screw up the mind of our second driver.
"Because if he's up in the front, and he's leading the race… That's why I don't want to call it."
Experience the full coverage of the FIA Formula One season throughout 2017 on FOX Sports Play, where you can watch LIVE races from angles, unlike any other, highlights, interviews, behind the scenes and much more. Don’t miss it!