The news that Rio Ferdinand’s contract will not be renewed by Manchester United this summer comes as little surprise and further increases the sense that there will be a major overhaul of the squad this summer. With Nemanja Vidic’s exit having long since been confirmed, the center of the just-deposed champions’ defense is set to be a main area of transition.

The loss of two of the club’s most experienced players, who were the bedrock of the defense for so long is a significant gamble and would be even more so if those currently at the club were to be relied upon. Phil Jones, Chris Smalling and Jonny Evans all have quality, but equally have failed to show on a consistent basis that they belong at the very level, in part due to frequent injury problems. It is hard to think that at least one experienced central defender will not be sought this summer.

Here are five players who may well be on the agenda.

Ezequiel Garay (Benfica)

The Argentina international has been linked with a move to Manchester United under the charge of both Sir Alex Ferguson and David Moyes, but has now suggested that his future this summer is uncertain. While he had a disappointing time with Real Madrid, Garay has impressed in Lisbon, notably in helping Benfica to the Europa League final this season, where he could further enhance his reputation in Wednesday’s final. Good on the ball, the 27-year-old would fit into the passing, proactive philosophy of expected new Manchester United manager, Louis van Gaal. His price tag is likely to go up if the mainstay of Argentina’s defense enjoys a good World Cup and even lifts the trophy this summer.

Mats Hummels (Borussia Dortmund)

Hummels is another player with plenty of ability when in possession. The Germany international has been linked with Europe’s biggest clubs in recent years and continues to be mentioned in connection with a move to Old Trafford. While he has a hefty reputation, he does experience lapses, notably in Germany’s defeat to Italy in the Euro 2012 semifinal. Even should United decide he is the defender to spend big on, Hummels is likely to prove unattainable. Having already lost Robert Lewandowski this summer, Dortmund will stubbornly resist losing another key player.

Davide Astori (Cagliari)

Having impressed to help Cagliari stave off relegation, Astori is widely expected to move onto a bigger club this summer. United are one of the clubs to be linked to the left-footed center-back, but Roma are thought to be very keen on keeping him in Italy. Astori, 27, came up through the ranks at Milan, but it was at Cagliari that he has made his name and continued to grow his reputation. While has seven caps for Italy, he has been left off of Cesare Prandelli’s provisional World Cup list. That snub could further convince Astori to seek more high-profile surroundings.

Eliaquim Mangala (Porto)

One United target that will be at the World Cup is France’s Mangala. The Porto man is one of the most sought after central defenders in Europe, with Manchester City having come close to landing him in January. Porto’s demand for £37 million saw a deal break down then, but City are thought likely to return to try and secure his signature in the summer, potentially putting them on a collision course with their local rivals. Yet, with Porto known for their tough negotiating stances, City could be forced to back away given their recent charge of falling foul of Financial Fair Play and thus hand the initiative to United.

Bruno Martins Indi (Feyenoord)

If Van Gaal decides to sign a player that he already knows well, then it is likely he will turn to Feyenoord youngster Martins Indi. The 22-year-old played a key role in Netherlands’ World Cup qualification campaign as Van Gaal again elected to trust in youth. His comfort on the ball has seen him play several games at left-back this season and that versatility could be an extra attraction, although he remains a more natural center-back. Latest speculation suggests that he is a leading target to replace Ferdinand, but Van Gaal will be well aware that his value could inflate after the World Cup.