“From lifting the World Cup to conquering a new language- my student's talent knows no bounds!” read her caption on the post with Alvarez.
“Impressive progress in such a short period of time. Very proud of my student!”
She also teaches Brazilian midfielder Arthur Melo, who joined Liverpool on loan from Juventus last summer.
Duque is fluent in an impressive six languages: Portuguese, English, German, French, and Spanish.
But while footballers have given her credit for improving their speaking skills, the WAGS are far more concerned about her services.
How Sara Duque became off-limits
Before starting her language learning service tailored for footballers, Duque became a lawyer in Belgium.
She continued sports medicine study in the United States before trying her luck at FC Porto as a football language coach. Now, she's willing to strike out on her own as a private teacher for Premier League's foreign players.
All the while, Duque has grown her Instagram account to a whopping 160k followers. She wows her following with a series of bikini-clad selfie snaps, and sexy gym poses.
Despite the red card from Premier League WAGs to drop her as a teacher, we don't think Duque will be hanging up the job any time soon.
On the contrary, this could be the start of many more recruits.