Four-time world champion Sebastian Vettel announced he'd be departing Ferrari at the end of the 2020-21 season earlier this month. Sainz, who is into his second season at McLaren, has since been confirmed as the German's replacement from 2021 onwards.
Sainz, a year older than Asensio, was born in Madrid and is an avid football fan who organises seven-a-side matches with his F1 mechanics and engineers when in London.
He revealed as much during his conversation with the 24-year-old playmaker, during a split-screen video published by Real Madrid on their official YouTube channel earlier.
Real Madrid's Asensio boosted by enforced break
He began their conversation by asking about Asensio, who has been recovering from a cruciate knee ligament injury which saw him sidelined from last July onwards.
Although he's yet to play in the 2019-20 campaign, the Spanish international remains upbeat and was honest when talking to his compatrot about his recovery.
In the video, he said: "It's going well. In the end this break has given me more time to train, rest the knee and it's going well really."
Asensio asked Sainz a question he's always wanted to know the answer to: what are F1 drivers' training sessions like?
In an intense sport that doesn't get the credit it deserves for being so physically demanding, Carlos didn't hesitate to stress the strain he puts his body through to stay in racing shape.
"Our training sessions are quite complicated: we must be the only sport in the world where we can't practice the sport that we do. My training is quite focused on cardio because in the car, even though it doesn't seem like it, our pulse goes between 150-180 and up to 200 at [racing] starts or when overtaking."
He proceeded to relate his situation to football, prompting a visible surprised Asensio:
"It's as if I told you, if the season starts at the end of August, you can only touch the ball three days, the first three in August and only the days you play."
During their FIFA match - both used Real Madrid - Asensio raced into a 3-0 first-half lead while they continued talking. Sainz asked whether Marco was aware that teammate and goalkeeper Thibaut Courtois is "crazy about Formula 1 e-sports", to which he replied:
"Yes, he told me he wanted me to play too, but I haven't played yet."
Sainz encouraged him to potentially try sometime in future, before discussing the form of Asensio's teammate Ferland Mendy, who has enjoyed a good first season at Real Madrid.
Sainz spoke about Mendy's impressive form, to which Asensio replied, "yes, and the first season is never easy."
Asensio felt bad and took it easy on Sainz in the second-half, but Carlos was still unable to score before full-time - then Carlos Sainz Sr entered the room and wished the Real Madrid man well as he continues his injury recovery.
Real Madrid are set to resume action early next month, after Spain's prime minister announced the 2019-20 season can continue from June 8.Published 24 May 2020, 00:50 IST