When Alonso departed Chelsea for Camp Nou in 2022, it was a low-cost addition that was viewed as a shrewd piece of business.
That is exactly how it proved to be, Alonso making 24 appearances either at centre-back or left-back as Barcelona won the La Liga title.
However, now 33 years of age, the former Chelsea star has dropped down the pecking order at the Catalan giants, his cause not helped by injury.
Just four starts and three substitute outings have been made in all competitions, his last outing coming as far back as November.
With Barcelona needing to cut costs at the end of the season and the Spain international being out of contract, it is a foregone conclusion that he will leave for pastures new.
According to Cadena SER, negotiations have already reached an advanced stage with regards to Alonso signing for Atletico Madrid.
The report suggests that there will be somewhat of a defensive reshuffle at Atletico this summer, with Mario Hermoso potentially departing on a free transfer.
Furthermore, 33-year-old centre-back Stefan Savic may also move on from Civitas Metropolitano despite earning regular game time during 2023-24.
Meanwhile, Caglar Soyuncu finds himself back in his homeland with Fenerbahce and it appears highly likely that he will be sold in the summer.
Why Alonso would likely settle at Atletico
Alonso is no stranger to the city of Madrid having been born in the Spanish capital and spent the early days of his professional career at Real Madrid.
Part of Alonso's reasoning to move to Barcelona in 2022 was his father having representing them during his playing days, and Atletico fall into the same category.
Up until last year, Alonso was still a part of the Spain national squad, but it appears likely that he will be able to fully focus his attention on club matters from next season onwards.
The same report has claimed that young Valencia centre-back Cristhian Mosquera may be targeted by Atletico, providing that they can negotiate a deal with his current club.