Brendon Hartley has all but secured another race with Toro Rosso in Formula One.

The Italian outfit has confirmed to our newsroom that the Kiwi driver will most likely race for them at next weekend's Mexican Grand Prix.

Hartley only joined Toro Rosso earlier this week as a replacement driver and finished 18th fastest in qualifying at the US Grand Prix in Austin.

Team Principal Franz Tost says he's shown a huge improvement from when he was Toro Rosso's test driver in 2009, and has gelled well with the team.

Tost says if Hartley continues to show improvement, then he'll be a driver for them next year.