Carlos Sainz Jr. says Toro Rosso is beginning to slip back through the pecking order, as rival teams gradually introduced engine upgrades across the course of the season.
Toro Rosso has switched to using year-old Ferrari power units this season, and accepted before the start of the year that it would gradually regress through Formula 1's midfield.
Toro Rosso is currently sixth in the standings but Sainz Jr. is wary that the team is now holding on in the scrap.
"It’s going to be tough," he said, when asked of rivals introducing engine developments.
"In Australia we managed to qualify P5 and P7 and now in places like Canada or Azerbaijan we will struggle to get into Q3, so for sure we are going a bit backwards.
"We haven’t put that many upgrades on the car since Australia, but thanks to the good effort of the team we are not that much falling back, no?
"And we are still in the game, we are still fighting for P5 in the Constructors’, with the same car as in Australia, which is a huge achievement, even though you take into account how many upgrades Force India and McLaren are bringing and we are still there trying to hold on."
Sainz Jr. has already matched his 2015 points tally of 18, having finished in the top 10 across the most recent three Grands Prix.