Toro Rosso boss Franz Tost is confident that his new driver line-up will blossom in 2018.
"I am more than happy with both of the drivers," he told RACER magazine. "I think they have a lot of potential.
"If we, as a team, provide them with a good, competitive car, then they will be there. I am convinced about this."
Pierre Gasly completed five races last season after taking over from Daniil Kvyat in Malaysia. Meanwhile, Brendon Harley took part in four races once Carlos Sainz moved to Renault.
Neither driver managed to finish in the points during their first outings with the team, but Tost said that was to be expected.
"To come into Formula 1 during a season is always a difficult task," Tost pointed out. "All the other drivers did thousands of kilometers in their cars – they are used to the cars, they know the team and they know everything.
"[For Gasly and Hartley] to then come in as a newcomer makes life quite complicated.
"It was a difficult period of time for them to come into," he continued. "Our car was not as competitive as it was at the beginning of the season.
"We brought new parts and upgrades to the tracks, but it looks like our direct competitors did a better job.
"On top of that we were suffering with reliability issues, which meant they always had to start from the back of the grid."
But Tost believes that giving both drivers their first Grand Prix opportunities at the end of last year will help them in 2018.
"It was really very important for both drivers to do the races at the end of the season," he said. "They are aware of what they can expect this coming season, [so] they are also aware of where to work themselves.
"Both drivers are really fast," he added.
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