Following a number of frustrating outings for the Italian team after his switch with Max Verstappen from the Spanish Grand Prix, Kvyat helped Toro Rosso back in to the points with a strong drive at the recent Marina Bay event.

And with the Russian having defended well against Verstappen, Tost has no doubts that Kvyat has made a breakthrough in getting back belief in his own ability to deliver.

"Exactly," Tost told Motorsport.com. "Just to come back and get the self-confidence back was important, and I think this is a good step forward."

Although Tost had hoped for a bigger points haul from Singapore, with Carlos Sainz having suffered a start-line incident with Nico Hulkenberg and a broken ERS, Kvyat's run to ninth place was labelled as very strong.

Tost added: "Daniil did a fantastic race. He recovered very well and he fought quite well against [Fernando] Alonso and against Max. He defended really well and in the end unfortunately he could not manage to pass Perez because he was too slow on the straight.

"I am very happy for him because he showed a good race and scored good points. I expected more than two points from the race, but this is how it is."

Car limits

Tost acknowledges that Toro Rosso will face a tough time to keep scoring big points over the remainder of the season because of its power deficit against its main rivals.

And although there have been doubts about the progress a new B-spec package that arrived at the German Grand Prix has delivered, Tost said he could have no complaints against his technical team.

"I don't want to go into detail there and comment," he said, when asked about the latest feedback on the update. "We have a real good car from the aerodynamic point of view. We showed that here and there is nothing else to say or to analyse."