Formula 1 teams will be quickly up to speed this week as pre-season testing shrinks to just three days in total.

"You can't do big tests - you'll have to set times as quickly as possible," Dr Helmut Marko, a top official at world champions Red Bull, told f1-insider.com.

Mere days then separate the official three-day test, concluding on Saturday, from next weekend's 2023 season opener at the same Bahrain circuit.

"It's important that you already know at the first race a week later which setup you are going to start the weekend with - both in qualifying and in the race," Marko added.

However, the 79-year-old former F1 driver admits that the teams will only really "let their pants down" in qualifying.

"But due to the short testing time, there is much less leeway than before," Marko said.

At the top of the field, Red Bull - and back-to-back world champion Max Verstappen - is expected to start as clear 2023 favourite.

Opinions are split as to whether Ferrari or Mercedes will put up the strongest challenge.

"Mercedes are brave in sticking with their concept," Marc Surer, another former F1 driver who is now a German-language broadcaster, said.

"After all, they had big problems with porpoising. The rule changes could help them now but I still rate Ferrari more highly."

As for the rest of the field, Surer said that question has a "big question mark" after it.

"McLaren, Alpine, Sauber, Alpha Tauri and especially Aston Martin are still difficult to rate at the moment," said the Swiss. "The tests will answer only a few questions before the start of the season."

According to Ho-Pin Tung, a Dutch-born Chinese former F1 tester, "many" of the 2023 cars he has seen in detail so far "are inspired by the Red Bull concept".

"But I also realise that the teams don't want to reveal everything yet," he told nu.nl. "The cars could look completely different when we see them in testing." body check tags ::