The difference between the medium and soft compound Pirelli tyres is so great that it completely changes a car's handling says Felipe Massa.
The Brazilian was seventh fastest in Friday's first practice for the Chinese Grand Prix, 1.378 seconds off the pace of Nico Rosberg's Mercedes. All the teams ran on medium compound tyres during the session and Massa immediately complained of graining on his front right tyre.
However, with a switch to soft tyres for the second session, the Ferrari's came to the fore with Massa topping the charts and Fernando Alonso third fastest.
While unhappy with the F138's performance on the medium compound, the 31-year-old believes that the results on the soft tyres give the team reason to be optimistic ahead of Sunday's race.
"Today, I immediately had a good feeling in the car and even if, at the start, I was not completely happy with the performance of the Medium compound and we were not as quick as our rivals, the times were good all the same," he explained.
"When I fitted the Softs, the car improved a lot and this meant I was able to set the fastest time of the day. It was impressive, like driving two completely different cars.
"Our race pace looks competitive, the car is handling well on both types of tyre and degradation was not excessive, even if the higher wear rate of the Soft compared to the Medium compound will be an important factor when it comes to choosing the right strategy. I feel confident and hope that the whole weekend can keep moving in this direction".
Given the variance in the tyre performance, Alonso believes that the grand prix will be won and lost by race strategy.
"Once again, tyres will play a key role in this Grand Prix because of the high level of degradation over a long run. We will have to ensure we pick the right strategy for Sunday, as well as deciding on which of the new parts we tried this morning to fit to the car. As usual, we can expect a long evening studying the data," said the Spaniard.