Undoubtedly, defenders are apparently becoming a “valuable” commodity and english premier league outfits are busy planning possible moves to bolster and strengthen their back-lines. With the opening of the summer transfer window last Saturday, Premier League club sides are now weighing up “big money” moves and deals with EPL champions Chelsea's proposed $78.8m offer for Juventus left-back Alex Sandro. Arguably, that's the most eye-catching offer for a defender this summer. Here's a look at the compiled list of the four biggest fullback targets that are been heavily linked with a move to the English Premier League:

Kostas Manolas — AS Roma

Manolas has been of interest to Chelsea for some while now and the Premier League champions may finally be set to make their move for the defender.

The Greece international seemed set for a $33.6m move to Russian Premier League side FC Zenit Saint Petersburg, managed by former Manchester City manager Roberto Mancini, but a deal has stalled because of a dispute over personal terms. This has apparently left the door open for Chelsea to enter the race, in an attempt to lure Kostas Manolas to Stamford Bridge, as they look for reinforcements following the departure of John Terry and seemingly imminent exit of Nathan Ake.

Leonardo Bonucci — Juventus

Premier League champions Chelsea are interested in the Juventus center back, whom the Blues manager Antonio Conte worked with in Turin. However, while Conte would love to get a deal done, breaking up Juventus star trio of Georgio Chiellini, Andrea Barzagli, and Leonardo Bonucci looks unlikely.

Current Juventus head coach Max Allegri recently backed the Chelsea target as the Italian club's captain in waiting.

Alex Sandro — Juventus

While Juventus were not planning on finding an ideal replacement for the highly capable 26-year-old defender. Juventus have apparently admitted they'll not stand in the way of the Brazilian if he wishes to leave Turin.

Chelsea are clear favorites to sign Alex Sandro with the Blues set to pay a record $78.8m for the defender. Paris Saint-Germain have also joined the race and it looks as if it'll be a tough fight between the two club sides for the Brazilian services.

Marquinhos — Paris Saint-Germain

Marquinhos flourished last term in his favored central role, following the departure of David Luis to Chelsea, and Manchester United have shown an interest in the Brazilian.

But, if Manchester United want to snap the 23-year-old defender, they face a tough fight as Juventus and Barcelona are also looking at the Brazil defender. However, Marquinhos has said he is happy with the French giants despite EPL interest seemingly coming every transfer window.

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