Real Madrid goalkeeper Keylor Navas has joined PSG for a reported fee of €15 million (£14m/$17m), while Alphonse Areola has moved in the opposite direction on loan.
The Costa Rica international also claimed the 2017-88 UEFA Club Football Award for best Goalkeeper, and was named in the Champions League squad of the 2018 campaign, when Gareth Bale's double over Liverpool helped the club to a third successive title.
Navas then lost his number one spot at the Santiago Bernabeu upon the arrival of Thibaut Courtois last summer, and has now joined the Ligue 1 side at the expense of Areola, who has made the switch to Madrid on loan.
France international Areola leaves on a season-long agreement, with no option to purchase coming with the deal.
The 26-year-old spent several years in the PSG youth sides before making his senior debut in 2013 as the club went on to win the league. The goalkeeper then picked up two more Ligue 1 titles, along with back-to-back French cups.
Areola was also a member of France's 2018 World Cup-winning squad, having previously made his international debut in a man-of-the-match performance against Germany in a UEFA Nations League meeting last year.
Despite starting in three of PSG's four league games this season, Areola has made the switch to La Liga, where he looks set to act as back-up for first-choice Courtois.
Former Chelsea youngster Marcin Bulka stepped in as shot-stopper for Friday evening's 2-0 victory over Metz, a win which sent the French champions to the top of the table on goal difference.
The 26-year-old made 29 Premier League appearances as the Cottagers were relegated to the Championship last campaign, having played for the Spanish side 160 times over a four-year spell.