Carlos Sainz admits he expects to have a hard time matching the pace of new Renault Formula 1 teammate Nico Hulkenberg in the remaining four races of the season.
Hulkenberg has impressed in his first season at the Enstone-based team, scoring 34 points to lie 10th in the drivers' championship, 14 behind Sainz.
The Spaniard, who is moving across to Renault early to replace Jolyon Palmer for the remainder of the 2017 season, is under no illusions of how challenging it will be up against the German.
"It's going to be difficult because has been driving a car for 16 races that I haven't driven," he said when asked if he felt he would be able to take the fight to Hulkenberg this year.
"It will take time to adapt to it. I would like to do it as soon as possible but I am convinced it will take a bit of time of adaptation.
"My target is to be on pace as quickly as possibly, but it doesn't come for free.
"There will be a lot of hard work, analysis, understanding with the engineers how to drive the car, and if it happens, it happens."
There had been suggestions Sainz could have replaced Palmer as early as Malaysia, but it failed to materialise as the latter pushed to keep his seat before finally being ousted after last weekend's Suzuka race.
But Sainz said he was not dismayed at not having been able to make the switch to Renault earlier, and that he would have been happy to see out the current campaign at Toro Rosso if called upon to do so.
"I think it's the right time [to make the switch]," he said. "Things happen as they happen, there's no need to say, 'I would have liked earlier or later'.
"I was happy to stay at Toro Rosso and I was happy to move to Renault. I was quite unbiased in that regard.
"Now it finally happens, it makes me happy, of course, because it gives me a chance. But nobody explained to me the delay."