Former Red Bull reserve driver Brendon Hartley is in contention to compete for Toro Rosso at next week’s US Grand Prix.
Earlier this week, Toro Rosso confirmed that they had handed a recall to Dany Kvyat to replace Carlos Sainz after the Spaniard moved to Renault with immediate effect.
However, it was subsequently revealed that team-mate Pierre Gasly will also miss the race in Austin, Texas, due to competing in Japan at the final round of the Super Formula series.
Gasly raced for Toro Rosso in both Malaysia and Japan, as boss Franz Tost considers his driver line-up for 2018.
Widespread reports have now indicated that New Zealand’s Hartley is the leading contender to replace Gasly.
The 27-year-old has previous experience in Formula One after he was Red Bull’s back-up driver for both the 2009 and 2010 campaigns, before being dropped from the company’s driver development program.
Gasly remains favourite to drive full-time for Toro Rosso next season and is expected to return for the final three races of the season.