Sauber admitted that the Chinese Grand Prix was a huge missed opportunity for it, with Pedro de la Rosa having moved into the top five early on only to retire with another mechanical failure.
The Spanish veteran was one of the handful of drivers who guessed correctly and stayed out on slicks in the initial shower. That put him up to fourth, but then he stopped on lap seven with smoke from the rear of his Sauber.
"Of course I am deeply disappointed," said de la Rosa. "We made all the right tire decisions. I started on slicks and managed to stay out in the drizzle. I enjoyed overtaking and then I was in fourth. When you are in a situation like this, you really have to finish. We missed a great chance today."
De la Rosa suspects the issue was another engine failure.
"I don't know what exactly happened," he said. "I felt there was something wrong with the engine and then stopped in Turn 9."
Technical director James Key was also frustrated to see de la Rosa's good drive end so early.
"Pedro was driving an excellent race, he made a great call on the tires and the team went with that decision," said Key. "He stayed on the dry option tires while others changed to wets, which was a very good call by the driver and the team. He ended up fourth -- looked fairly strong, was battling with Vitaly Petrov and the lap times were good. Sadly, there was a problem with the car. It is engine related but we can't say whether it's a specific engine problem or a problem related to the chassis. We still need to analyze that when the car comes back.
"It was a points opportunity today, but unfortunately it didn't happen."
Kamui Kobayashi in the sister Sauber was taken out by the spinning Tonio Liuzzi on the first lap.