Red Bull drivers Daniil Kvyat and Daniel Ricciardo say Renault has made progress with its engine following practice for the Malaysian Grand Prix.
The team's chiefs were very critical of the French power unit after the Australian Grand Prix, with Christian Horner labeling the engine as "undriveable".
However, the team seemed to take a step forward on Friday, with Kvyat hailing the progress made after posting the fourth fastest time in the afternoon.
"We reacted, not overreacted. We reacted and we're in the right direction right now at the moment," said Kvyat.
"There's plenty of work ahead, many areas, but the right steps are being made and this is encouraging."
When asked if Renault's engine driveability had improved, he said: "Like I said, good steps have been made, there are more steps to come, which must come if we want to go ahead.
"But the right steps and the right direction are most important and this is what is happening at the moment.
"We are obviously more satisfied, but we're never fully satisfied until things are perfect."
Ricciardo hits trouble
Red Bull has reverted to the engine settings it used during testing, and Ricciardo said the car had taken a good step forward.
The Australian's day, however, was cut short in the afternoon after he spend a lot of time in the garage as his team worked on engine-related issues.
"Some things are definitely positive and the bulk of the driveability issues we had in Melbourne are a lot better now," he said. "The car was a lot nicer to drive.
"We got to do a few set-up things this morning then we had a few issues this afternoon which limited our running.
"But there are some positives and we got some good feedback from Dany; he wasn't too far off the pace of the Ferrari's so that's good and encouraging for tomorrow."