Daniil Kvyat has his fingers crossed his growth spurt is over.
A cursory look at the Russian's formative career, including his GP3 title last year, shows that the then lanky teenager was 175cm tall.
But other, perhaps more up-to-date F1 resources are showing the impressive Kvyat at 180cm -- the 5cm difference meaning he is either an average 5 foot 9, or a quite-tall 5 foot 11.
Dr Helmut Marko, in charge of Red Bull's driver development programme, has been quoted as saying the young Russian is indeed growing very quickly.
It has raised fears Kvyat might keep growing and hurt his career by no longer fitting easily at the wheel of today's F1 cars.
"Of course yes," he told Speed Week, "I am one of the taller drivers.
"I have had a growth spurt, but it's over now, I think," Kvyat added.
Marko has also suggested that Kvyat, while clearly the standout surprise among the latest F1 rookies, has been lucky to make his debut in 2014 rather than perhaps a year earlier.
"Daniil Kvyat is a very good driver," he told the Guardian. "But he's young and if he jumped in last year's car he would not have finished a grand prix without being completely exhausted.
"Now he can finish because the demands are so much lower," Marko added.
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