Barcelona have announced the arrival of Miralem Pjanic in a £55 million deal from Juventus.
The 30-year-old will move to Camp Nou at the end of the season, with Arthur heading the other way.
A deal between the two European giants was reached last week that will result in Pjanic swapping clubs.
It's a deal not commonly seen in football. Juventus will pay Barcelona €72 million plus €10 million in variables for Arthur, while Barcelona will pay €60m (£55m) for Pjanic.
Both players will remain at their current clubs for the remainder of the 2019/20 season.
The coronavirus pandemic has caused financial uncertainty and Juventus would have struggled to sign Arthur without agreeing to let one of their highest-earners leave.
And with Barcelona having kept eyes on Pjanic for some time, the deal makes sense for both clubs.
Arthur, 23, was initially reluctant to leave Barcelona, but a breakthrough on Saturday evening enabled the deal to be completed.
Pjanic, meanwhile, has played a major role in Juventus' recent success, winning three league titles and the Coppa Italia twice since joining from Roma in 2016.
Pjanic is a class talent but the swap won't please ever Barcelona supporter.
The Bosnian midfielder is 30 years old, seven years Arthur's senior, and isn't a significantly better player than the departing Brazilian.
Adding to that is the fact that Barcelona have an ageing squad that is in desperate need of young talent.
Getting rid of Arthur and bringing in Pjanic won't help the reigning Spanish champions become any younger.News Now - Sport News