#4 Toby Alderweireld (Tottenham)
Highly sought after by Manchester United during most of the last transfer window, Jose Mourinho earmarked the Belgian as one of his primary defensive targets, but The Red Devils were rebuffed in their attempts to land their man by Daniel Levy.
Alderweireld remained at Spurs, but it is highly likely that he would depart the club on a Bosman come the end of the season (unless a club swoops in for him during the winter window).
The 29-year-old Belgian international has been a colossus in defence for club and country and has firmly established himself as arguably the finest centre-back in the Premier League since his 2014 transfer from Atletico Madrid (which explains the desperation to get him by Manchester United).
United might not have gotten him at the conclusion of the last window, but come May next year, they could well get an even better opportunity to sign him for nothing.