Amid a summer window of prolific spending at Arsenal, the Gunners are also expected to say goodbye to club captain Thomas Vermaelen.

Indeed, the Belgium international still holds the armband at the Emirates, but a mixture of recurring injuries, poor form and the talismanic partnership of Laurent Koscielny and Per Mertesacker saw him make just seven starts in the Premier League last season.

The 28 year-old has been known to be considering his options for some time, and recent speculation suggests both Liverpool and Manchester United are baying for his signature.

But should Vermaelen leave, Arsenal will undoubtedly need to source a replacement with only three centre-halves, including the want-away defender, currently on the Emirates roster.

With that in mind, here's SIX replacements Arsene Wenger should consider this summer.

Vermaelen

[/ffc-gallery]

FABIAN SCHAR

Fabian Schar

Arsenal have been strongly linked with Fabian Schar before, and should Thomas Vermaelen leave the Emirates this summer it would be incredibly surprising if Arsene Wenger didn't revive his interest in the Basel defender.

Statistically, the Switzerland international was the best defender in the Champions League last season, as detailed below...

schar cl

And his World Cup performances weren't too bad either, making eight interceptions during two outings at Brazil 2014.

The 22 year-old has an interesting knack for scoring goals, even taking up spot kick duties for Bebbi:

//www.youtube.com/embed/MIe6I323HPc

And also netted this incredible strike as a youngster at FC Wil:

//www.youtube.com/embed/dH1mLudmGgg?autoplay=1&loop=1&playlist= dH1mLudmGgg

A proactive, forward-thinking centre-back with considerable quality on the ball, Schar would fit perfectly with Arsenal's possession-based philosophy.

But there are a number of suitors allegedly baying for his signature this summer, including Barcelona, Manchester United and local rivals Tottenham:

WINSTON REID

Winston Reid

In terms of Vermaelen replacements with proven Premier League pedigree, the stand-out option remains West Ham's Winston Reid, whom the Gunners were closely monitoring ahead of the January transfer window:

A move failed to materialise due to the New Zealand skipper being sidelined with an ankle injury, and by no great coincidence, the Hammers' league form tanked in his absence.

The season prior, the 26 year-old claimed the Hammer of the Year award at Upton Park, celebrating the enormous progress he's made since first joining the Irons after impressive showings at the 2010 World Cup.

Despite his sideline bout, Reid was in good form last season, as detailed below:

Winston Reid

And although the All Whites centre-half may be more rugged than your average Arsenal defender, that difference in style offers Arsene Wenger some much-needed variation at the heart of defence.

Furthermore and most importantly, Reid's contract is set to expire in 2015 and he's continually delayed on a new deal - meaning he can be picked up for cheap this summer.

But Hammers chairman David Sullivan is keen to tie the 6 foot 3 centre-back down to new terms:

MATIJA NASTASIC

Matija Nastasic

According to the tabloids, Arsenal have already targeted a direct replacement to Thomas Vermaelen in Manchester City's Matija Nastasic:

The 21 year-old is an impressive talent, having already plied his trade with Fiorentina in Italy and the Premier League champions. Here's a short clip highlighting Nastasic's strengths:

//www.youtube.com/embed/LxnfKoOWmWE?rel=0

But the Serbia international will be concerned that his progress is being stifled at the Etihad - injuries and the rise of Martin Demichelis saw him make just 14 Premier League appearances last season, and he now has to contend with all-but-confirmed £32million signing Eliaquim Mangala.

An Emirates switch would be an interesting move for Nastasic. He lacks physicality but is clearly a very intelligent defender, also offering significant Champions League experience . And as viewable below, his quality in possession is second to none:

nastasic

But the Gunners face stiff competition for his signature, with several Serie A sides including Juventus, Inter Milan and Roma also strongly linked:

TOBY ALDERWEIRELD

Alderweireld

The Gunners could swap one Belgium international for another if Arsene Wenger decides to reignite his interest in Toby Alderweireld from last summer.

The former Ajax star joined Atletico Madrid instead in a £6million deal, but the Mattress Makers' sensational rise to La Liga title and Champions League final glory saw him make just ten league starts last season.

No doubt, the 25 year-old is a talented defender, capable of playing at centre-back or right-back (as he did for Belgium at the World Cup) and famed for his consistency, as visible below:

Alderweireld

A product of the total football academy, Alderweireld comes with an impressive all-round game. Here's a look at him in action for the Amsterdam outfit:

//www.youtube.com/embed/RFL2-xH2cis?rel=0

The 6 foot 2 defender has already made plenty of noise about leaving Vincente Calderon and was reportedly offered to Napoli in January.

But recent speculation suggests Liverpool are currently leading the race for his signature:

NEVEN SUBOTIC

Neven Subotic (2)

Jurgen Klopp appears determined to hold onto World Cup-winning centre-back Mats Hummels this summer, but that in turn could spell a departure for fellow Borussia Dortmund defender Neven Subotic.

The 25 year-old has been linked with Chelsea, Manchester United and Manchester City in the past, earning a reputation as one of Europe's most underrated defenders as the unassuming-yet-sturdy partner to Hummels.

The Serbia international was in customarily strong form last season until his campaign was cut short through injury:

Subotic

Here's some highlights from last term, with Subotic's pace, tackling ability and composure in possession particularly standing out:

//www.youtube.com/embed/YV1uB16MEgQ?rel=0

But that eight-month sideline spell saw Greece defender Sokratis thoroughly excel as understudy, and it remains to be seen who will be given the first team berth on a regular basis next season.

With three high-quality centre-backs to choose from and just two years left on Subotic's contract, a bid around the £15million-£20million mark could convince the Black-Yellows to sell.

FEDERICO FAZIO

Federico Fazio

Another, slightly more outlandish, option said to be on the Arsenal radar is Sevilla's towering centre-back Federico Fazio:

Measuring in at 6 foot 5 whilst also capable of playing in defensive midfield, the La Liga man-mountain has drawn many comparisons with Per Mertesacker.

The Argentina international was in strong form last season too as Los Palanganos claimed the Europa League title, as viewable below:

fazio

Oh, and don't mess with him, or he'll punch you in the stomach:

The 27 year-old is a well-experienced, composed defender that could certainly do a job for the Gunners.

Furthermore, according to TalkSport, Fazio's release clause stands at an incredibly cheap €10million.