António Félix da Costa is likely to make his Formula 1 debut in 2014, if current Toro Rosso driver Daniel Ricciardo is promoted to Red Bull.
The 21 year old Portuguese driver has been part of the Red Bull junior team since the middle of last season and is on the radar ahead of 2014.
"António Félix da Costa is one of the candidates, but let's wait for Red Bull’s decision," STR team principal Franz Tost told TotalRace.
"If they take Daniel, we will assess the choice for our second cockpit."
French racer Jean-Eric Vergne is set to be retained by Toro Rosso for next season.
Da Costa, whose position at the team hinges on Ricciardo's future, is currently in fifth place in the Formula Renault 3.5 Series.