Hakimi was hardly short of offers of first-team football this past summer, despite only making nine La Liga appearances in his breakthrough season with Real in 2017/18. The Madrid outfit wanted him to learn on the job, and so too did the man keeping him out of the side - himself a former Bundesliga pro.
Taking on Carvajal's words of encouragement, 19-year-old Hakimi opted for a two-year loan move to Borussia Dortmund. Two games in, his decision has been fully vindicated.
Watch: Highlights of Dortmund's win over Nuremberg
Ok, strictly speaking it's six matches - but with a 2018 FIFA World Cup hangover to get over, a new football culture to learn and an old-hand to overthrow on the right-hand side of the defence in Lukasz Piszczek, Hakimi has had to bide his time. Happily, his patience has paid off.
On Bundesliga Matchday 5, Hakimi put in a Carvajal-esque display up and down the BVB right, capped by a heat-seeking debut goal from 18 yards, as Dortmund thumped Nuremberg 7-0.
A trip to Bayer Leverkusen provided a much sterner examination of the industrious Moroccan's credentials three days later, but he passed the test with flying colours. Indeed, it was his assist that enabled Barcelona loanee Paco Alcacer to put BVB ahead for the first time - the Black-Yellows having trailed 2-0 after 39 minutes - in a barnstorming 4-2 win.
"He's playing so well," said Dortmund head coach Lucien Favre. "He's great going forward and he does a good job at the back. He played at left-back for Morocco, but prefers to play at right-back. He has so much potential."
Great attitude and a well-deserved win. Now it’s time to think about the @ChampionsLeague // Gran actitud del equipo y victoria muy merecida. Ahora toca pensar en la Champions League 💪🏾🐝 #BVB pic.twitter.com/xbyoF2yAXj— Achraf Hakimi (@AchrafHakimi) September 29, 2018
That might explain why, from a Real perspective, he is only at Dortmund on loan. He could quite easily have landed elsewhere after a handful of eye-catching World Cup run-outs with Morocco, but Dortmund's reputation coupled with Carvajal's career-shaping stint in the Bundesliga with Leverkusen made up his mind for him.
"I had a lot of offers, but Dortmund's was the one that had be convinced," Hakimi said. "The team likes to play very attractive football and they try to make young players better. I had Carvajal in front of me at Real, but he told be to make the most of the opportunity: go there, play and enjoy it."
Carvajal should know. After all, it was he who blazed the trail Hakimi is now treading. The Spain international played 32 times for Leverkusen on loan in 2012/13 and made huge strides in his development; leaps so big that his parent club had him fast-tracked back to Madrid after just one season in Germany.
"Yes, it is something that I thought about when coming here," Hakimi said of his Spanish mentor and playing idol's route to the top. "I thought that it had helped Carvajal a lot that he came to play in Germany at such a young age. For me he's the best in his position, but Piszczek has been one of the best for years now, too. Hopefully I can also learn from him."
Hakimi's clearly done that already. His defensive discipline, positional awareness and willingness to attack are all Piszczek hallmarks - and the best thing? Received wisdom states he won't hit his peak for another eight years.
Until then, he'll continue to soak up all the information the likes of Carvajal and Piszczek throw his way. Just don't be surprised if Hakimi is soon the one delivering lessons on what it takes to be one of the world's best right-backs.