Ake made his first-team debut for the French club in 2019 and went on to make 26 appearances across all competitions, including four in this season's UEFA Champions League campaign.
At the other end, Italy youth international Tongya spent the last 11 years with Juventus' academy and was a regular feature in the club's U-23 side this season.
Zlatan Ibrahimovic for Samuel Eto’o + £35m and Alexander Hleb on loan (Inter - FC Barcelona)
Francesco Coco for Clarence Seedorf (Inter - AC Milan)
William Gallas for Ashley Cole + £5m (Arsenal - Chelsea)
Ricardo Quaresma for Deco (FC Barcelona - FC Porto)
Luis Garcia and £27m for Fernando Torres (Atletico Madrid - Liverpool)
David Luiz for Nemanja Matic + £20m (Chelsea - Benfica)
Henrikh Mkhitaryan for Alexis Sanchez (Arsenal - Manchester United)
Roberto Carlos + £1m for Ivan Zamorano (Inter - Real Madrid)
Ian Wright for some weights (Crystal Palace - Greenwich Borough)
Jose Antonio Reyes for Julio Baptista (Arsenal - Real Madrid)
Scroll through the gallery to see 10 of the biggest swap deals in football history >>>