Ferrari, Mercedes face engine concerns for Monza

All six Mercedes-powered cars took the new Phase 3 power unit on Friday morning in Belgium, with the intention of making it to the end of the season with no further changes and thus no penalties.

However, Racing Point's Sergio Perez suffered a failure in FP2, and then Robert Kubica had a different issue in his Williams at the start of qualifying.

Both drivers had to revert to Phase 2 units for the race while the damaged examples were returned to HPP in Brixworth for analysis.

Mercedes boss Wolff admitted that there were concerns about the other cars heading into the race, and said pending an investigation the situation was not resolved.

"It didn't compromise us massively. It did a tiny bit," Wolff said.

"We were not taking any risks in the race. But it was certainly not a comfortable situation. The failures looked to be different and are not analysed and understood as of yet."

Ferrari introduced its new engine at Spa only in the Haas cars of Romain Grosjean and Kevin Magnussen, and the Alfa Romeo of Antonio Giovinazzi, prior to its planned deployment with the works cars at Monza.

However, Giovinazzi suffered a failure in qualifying on Saturday, and Ferrari team principal Mattia Binotto admitted that it was a cause for concern.

"That's a good point, no doubt," he said when asked by Motorsport.com. "We need to analyse what happened because one of these failures should be down to something wrong, quite detectable.

"The engine will be back tomorrow [Monday] in Maranello, the first need will be to disassemble it and try to understand. We've got a few days still to react. But yes, it is a concern."

Earlier in the Spa weekend Binotto stressed that introducing the new engine with customer cars was not a data gathering exercise prior to deploying it with the works team, as it should already be proven.

"The reason we are anticipating is not to get data," he said when asked by Motorsport.com. "By the time that you introduce a unit it should be fully reliable, homologated and validated on the dyno.

"So the reason why we are introducing is simply we are on different scenarios in terms of allocation, in terms of mileage, and certainly by splitting as well the building of the engines makes it a lot easier at the factory."

While the works cars are scheduled to take the new engine in Spa, Alfa Romeo boss Fred Vasseur told Motorsport.com that there are no plans for Kimi Raikkonen to upgrade for the Italian manufacturer's home race. Any future change will earn the Finn a grid penalty.