Mercedes may delay engine upgrade... again...

Mercedes may delay engine upgrade again, as it tries to get to grips with Ferrari's breakthrough.

Mercedes team principal Toto Wolff has admitted that his team do not know how Ferrari have made their recent power breakthrough.

Now, the team are considering delaying their power unit upgrade introduction ahead of the two upcoming races at Spa and Monza.

Asked if he understands what Ferrari have done to improve their performance so much, Wolff replied: "No. We just see that there is much more performance over the last few races that has been increasing and increasing.

"It sounds like I am a broken record, reminds me of other individuals that have sung that over the last years. And I don't want to go there at all. We just need to really push hard on the chassis side and on the engine side and find that additional performance. It's there. It's not trivial, on the contrary, it's very complex. But it's there."

Mercedes even delayed their first power unit upgrade this season, which was scheduled for the Canadian Grand Prix but it didn't arrive until a couple of weeks later in France.

Normally, teams tend to upgrade their new power units when the Formula One season resumes after the summer break as Spa and Monza are two of the most power-dominated tracks on the F1 calendar.

It looks as if Ferrari will give Sebastian Vettel and Kimi Raikkonen their upgrades as they already tested it last weekend with Sauber and Haas.

Wolff isn't sure, though.

"At the moment we are in an interesting phase on the third engine and we are trying to extrapolate how much performance gain we can find until Spa and Monza," Wolff added.

"Only once we know that number we will be able to decide whether we need to postpone or do something else."