Kiwi driver Brendon Hartley has received the firmest indication yet he will drive full-time in Formula One next year.
Soon after completing twin practice sessions for the Mexican Grand Prix on Saturday (NZT), Hartley and Frenchman Pierre Gasley were being promoted as the two men to be retained Toro Rosso in 2018.
Toro Rosso team principal Franz Tost barely minced his words when asked about his personnel beyond this season.
"We want to test them for the rest of the season because there is a high possibility that this will be the driver lineup for 2018," the Austrian told reporters.
"Brendon is a very high skilled driver, very committed, passionate for motorsport ... if we give him a competitive car, he will be there and he will also fight in Formula One for success.
"And I hope that especially next year we will bring together a competitive package that he can also fight for victories and good positions."
Tost confirmed Russian driver Danill Kvyat has left the Red Bull-owned team and is now a free agent.
Kvyat was dropped for this week's round in Mexico City, leaving room for Hartley to contest his second successive Grand Prix after placing 13th on debut at last week's event in Texas.
The comments followed a solid second practice session for the 27-year-old from Palmerston North.
Forced into the pits with engine problems early in the opening session, he responded with the 13th-quickest time in the mid-afternoon.
His best lap time of one minute 19.423 seconds was 1.622sec slower than Australian Daniel Ricciardo, who topped the timesheets for Red Bull.
Ricciardo pipped Championship leader Lewis Hamilton of Great Britain, who was also second-fastest in the first session behind Mercedes team-mate Valtteri Bottas.
Gasly suffered complications in the second session and was 19th fastest, nearly 4sec off the pace.
A third practice session and qualifying on Sunday (NZT) is followed by Monday's race, in which Hartley has set the target of a top-10 finish.