Carlos Sainz has admitted that his consecutive retirements in Australia and Imola left him suffering physically as the Miami Grand Prix weekend wore on.
After reaching the podium in Bahrain and Saudi Arabia, Sainz went more than a month without completing a race distance due to the two early DNFs.
As a result, Sainz faced a fitness battle in a hot and humid race at the Miami International Autodrome, made worse by a heavy practice crash that left him with a sore neck.
Sainz explains performance drop-off in Miami
Asked to reflect on the Grand Prix, and how his pace fell away between the first and second stints, Sainz revealed some physical struggles.
"There were no issues with the balance [of the car]," Sainz told media, including RacingNews365.com.
"It was tricky, because we couldn't keep up with Max [Verstappen] and the Red Bull, but from my side, it was more not feeling 100 per cent physically towards the end of the Medium [tyre] stint.
"[Over] the last five laps, I started to get a bit tired on the neck, and I couldn't push 100 per cent coming from the crash on Friday."
Sainz not looking for excuses after tricky spell
Sainz added that the challenge of adapting to F1's all-new cars, his lost track time in Australia and Imola, and his practice crash in Miami all combined to create the perfect storm.
"I will not use it as an excuse," the Spaniard went on to comment.
"It's just a matter of, maybe also like in the last two races, to get the neck and the body used to these Formula 1 cars.
"I had been a month without doing a full race distance and probably that, combined with the crash on Friday, just made me not able to push 100 per cent up until the Safety Car, more or less."
Sainz's third-place finish in Miami means he enters his home Grand Prix at the Circuit de Barcelona-Catalunya holding fifth in the Drivers' standings.
F1 Podcast: Is F1 at risk of alienating fans with its quest for a show?
RacingNews365.com F1 journalists Dieter Rencken, Mike Seymour and Michael Butterworth look back over the first-ever Miami Grand Prix, in which Max Verstappen once again beat Charles Leclerc – but was the racing less important than the show?