Mercedes Team Principal Toto Wolff has not ruled out the possibility of Lewis Hamilton and Valtteri Bottas taking grid penalties for exceeding the maximum allowance with multiple power unit elements.
The team opted to introduce their third power units of the season for the Belgian Grand Prix, meaning they are on the limit of the number of MGU-H, MGH-K and turbochargers that are permitted for 2021.
"Every engine is degrading and obviously you have a fresh one," Wolff told Sky Sports. "It has that notch more performance and if it gets really tight then you have to have this discussion.
"But at the moment, we're still counting on finishing it with three. In any case, it's very tight with three engines this season and it's something that everybody needs to monitor, whether you want to take a penalty to just have extra power."
Bottas topped the opening practice session at Spa-Francorchamps, running a low downforce rear wing. Hamilton was on a strong lap, which Wolff believes was on course to be the fastest time of the session, but was blocked by Nicholas Latifi going into the Bus Stop chicane and had to take avoiding action.
"Lewis' lap was compromised because we ran into traffic at the end, it was a bit of a hairy moment," said Wolff. "But I think we're in ok shape so far.
"We need to learn a little bit from the downforce levels. We ran the two different ones on both cars.
"I'm not quite sure that this [Bottas's rear wing] is the one we can run on the weekend. But it's definitely good to have done a back-to-back test and Lewis didn't put the lap in, he was a little bit faster."
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