Lewis Hamilton may be facing the next several grands prix without Mercedes' new specification engine.
That is despite the fact that, following the delay in Montreal, other Mercedes customers may already have the 'spec 2' power unit fitted for Paul Ricard.
"Yes, we will have the updated engine," Force India's Sergio Perez said in France.
However, Mercedes held the new unit back in Canada, citing "quality" issues.
And now it is not clear if Hamilton and his teammate Valtteri Bottas will have the engine in Paul Ricard.
"Let's wait and see what the team will decide tomorrow. I trust their judgement.
It wouldn't be so bad if we have to take the spec 1 again. It would be fresh and have more power. Engine performance has never been a problem for us," Hamilton said.
However, Hamilton would then need to use the 'spec 1' for several forthcoming races, as drivers are only allowed to use three different engines per season.
"We really want to put the new one in, but we're waiting to see if we can do it until tomorrow.
Every race weekend, the three strongest teams are fighting hard and any increase in speed we can get is important. We really hope to get that new engine," Finn Bottas added.
