Toro Rosso boss Franz Tost says the Faenza-based team has no excuses not to be close to its rivals at the top of the mid-field battle this year.

The junior bull squad has swapped its Renault engine for Honda power in a well-chronicled exchange with McLaren.

Honda believes significant progress is in the cards for its power unit this season following three years of dramatic under-performance with its former partner.

Still, uncertainly prevails around the Toro Rosso-Honda combo, but Tost is confident the Italian outfit can ultimately challenge for a spot in the top-five in 2018, despite also fielding an inexperienced driver line-up with Pierre Gasly and Brendon Hartley.

"We must be within the top five once more, it's the same story as in 2017," Tost told Racer's Chris Medland.

"Look, the first three positions are gone, forget it, this is another league and another world because they have much bigger financial resources and are much bigger teams.

"But then from position four onwards, everything is possible because Force India is running with a similar budget to us, Williams as well.

"I expect that McLaren will become quite competitive as well and Renault will make a step forwards, but it means from fourth position onwards everything is possible.

"Once more we have to build a good car, a competitive car, and we have the ingredients together to fight for a successful position."

On a relative basis, Toro Rosso's budget - while nowhere near the funding enjoyed by F1's front-runners - compares with the resources which Force India or Williams contend with.

This tells Tost where he thinks his team should be in the mid-field hierarchy.

"Regarding Williams and Force India at this stage – I don't know what they will achieve this winter and they might suddenly find £100million in sponsorship – we are working at a similar level and there shouldn't be any excuses from our side not to be close to them.

"To beat them is another question, but to be up there."

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