Carlos Sainz Jr says Toro Rosso needs to address the handling of its Formula 1 car for the Chinese Grand Prix after lacking confidence in a "weird" Melbourne season opener.
The Spaniard started and finished the Australian Grand Prix eighth, while Daniil Kvyat ensured the team started the year with both cars scoring points by finishing ninth.
Sainz was passed on his outlap by Sergio Perez for seventh, and though he caught the Force India again later in the race he reckoned he lost out through strategy and the car's performance.
"It was a pretty weird race," he said.
"When we stopped we returned ahead of Checo who tried to undercut us, but later flew past us on the straight.
"When you are lacking top speed so much it's hard to defend yourself.
"Then I had to let my team-mate through because my team asked me to, although he had to stop again, so we missed out on seventh place by a bit."
He added: "The cars let you show maybe a bit more of your potential in a certain race weekend when you're feeling particularly comfortable with the car.
"Honestly speaking, it hasn't been my case for the whole weekend, only on Friday was I at 100% feeling with the car.
"I lacked a bit of confidence so I couldn't really extract everything but it's a balance situation that hopefully we'll sort out for China."
Sainz said he had no problem moving aside for Kvyat, who was on an alternative strategy, because he was not sure he could have passed Perez late on without the delay anyway.
He also thinks Toro Rosso has work to do to get itself at the front of the midfield battle, having identified fifth place in the constructors' championship as its 2017 target.
"Williams showed that especially in race pace they're one step ahead," he said.
"The Haas, I don't know how they would've done with the soft, and the ultra-softs they were maybe a tenth faster a lap.
"Then it's us, I do believe we are faster than Force India, but they were that tiny bit cleverer than us with an [attempted] undercut."