The Gulf-owned European clubs, who have changed the landscape of football on the continent, were heavily involved in the hive of activity on the final day of the transfer window yesterday.
Owned by Royal Emirates Group, who are chaired by Sheikh Butti bin Suhail Al Maktoum, Getafe negotiated an option to buy back the Spanish midfielder, 24, they sold to Real last summer.
Leon, who signed a six-year deal after joining Real in a €10 million (Dh53m) transfer, was told by Jose Mourinho he did not fit into the Portuguese coach's plans. Reports put the buyout option at €6m.
Fellow Spanish club Racing Santander, who are bankrolled by Ahsan Ali Syed, the Bahrain-based entrepreneur, signed Greece midfielder Alexandros Tziolis, 26, on loan from Siena.
Boosted by the substantial investment since a takeover by the Qatar Investment Authority, Paris Saint-Germain, the French club, continued their spending spree by signing Diego Lugano from Fenerbahce on a three-year contract.
The Uruguay captain will bolster a squad that has been fortified by the arrival of €80m worth of talent in Javier Pastore, Jeremy Menez and Kevin Gameiro.
Manchester City, who were purchased by Sheikh Mansour bin Zayed in 2008, sought to trim their spiralling wage bill yesterday by allowing Craig Bellamy to join Liverpool and John Guidetti, the Sweden Under 21 international, to move to Feyenoord on loan deals for the rest of the season.
Shaun Wright-Phillips, the England winger, signed for Queens Park Rangers after failing to earn a first-team spot a City.
However, City did ensure they have cover for Yaya Toure during next year's African Cup of Nations by signing Owen Hargreaves on a free transfer.
* Compiled by The National staff with agency