By John Edwards, Sami Mokbel and Matt Barlow

Last updated at 4:39 PM on 30th August 2011

Arsene Wenger is closing in on 8million Germany centre-back Per Mertesacker and has completed a 6.2m deal for Brazil left-back Andre dos Santos as he belatedly bids to plug the holes in a leaky Arsenal defence.

Stunned by his side's collapse in Sunday's 8-2 mauling at Manchester United, and the outcry that followed from supporters and former players, Wenger has finally acted to try and rescue a season that is in danger of falling apart inside the opening few weeks.

Mertesacker will fly into London on Tuesday afternoon for a medical and to finalise his personal terms.

Next in: Per Mertesacker in action for Werder Bremen

Next in: Per Mertesacker in action for Werder Bremen

He has agreed a four-year deal with dos Santos, after meeting Fenerbahce's asking price for the attacking full-back, and stepped up his pursuit of giant Werder Bremen defender Mertesacker.

Sportsmail exclusively revealed earlier this month that the Bundesliga club's financial plight had forced them to consider offers for the cornerstone of their defence and that a 8.7m price had been set.

And Wenger is ready to pay it after being shocked by his injury-hit back four's shortcomings at Old Trafford and becoming embroiled in a bitter row with Bolton over a valuation on England centre-half Gary Cahill.

Wanted: Andre dos Santos is edging towards Arsenal

Wanted: Andre dos Santos is edging towards Arsenal

Claims by respected French newspaper L'Equipe on Tuesday  that a deal has been done for Mertesacker are premature, but there are growing signs the 26-year old could be an Arsenal player ahead of Wednesday's transfer deadline.

At 6ft 6in, the vastly-experiened defender would provide the physical presence so conspicuously absent during Sunday's rout, and he is renowned for putting his height to good use at set-pieces in the opposition's area.

There are misgivings, however, about a lack of mobility that could be exploited by the pace most leading Barclays Premier League teams have at their disposal.

Depressing day: Arsenal manager Arsene Wenger shows the strain at Old Trafford on Sunday

Depressing day: Arsenal manager Arsene Wenger shows the strain at Old Trafford on Sunday

The move for dos Santos came in the wake of widespread dismay within the Emirates at Wenger's decision to place his faith in injury-prone

England left-back Kieran Gibbs, after Gael Clichy left for Manchester City.
Gibbs duly picked up a hamstring injury and was ruled out at Old Trafford, leaving Armand Traore at the mercy of Nani. Both Traore and Carl Jenkinson were put to the sword, as Nani and Ashley Young ran riot.

Wenger reacted by splashing out on 28-year old dos Santos, who has 10 goals from 52 Fenerbahce appearances since joining them from Corinthians and has been capped 22 times by Brazil.

After flying into London for a medical on Tuesday, Dos Santos quickly agreed a four-year contract worth 40,000 a week and is expected to go straight into the team.

Exit door: Defender Armand Traore (left) has been allowed to join QPR

Exit door: Defender Armand Traore (left) has been allowed to join QPR

Here's what readers have had to say so far. Why not add your thoughts below, or debate this issue live on our message boards.

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Its no use getting exciting , for me its three years too late we have been screamin with The General Custer to buy buy buy for three years now we have sunk to our lowest he decides to puddle , sorry it don't wear on me , the man is a disaster here on wards and i feel when we had a chance to buy two three average players like the Santo's and Mertsaker's to complement our once great team he would'nt now its time for panic buying anything that we can get our hands on .. where are the Ribery's Sniejder's Mata's Kaka's etc etc , i could go on ,how many real world class players do we have righht now ? we have lost the confidence of all great players out there , until we change the Owner and get in line with the wages we will always be a second rate team , i predict top 8 at best this year ., we are in for a hard long season , and we must not forget the affect that massive defeat will have on the players that played that day .. Arsene is a walking bomb , he throw petrol on the flames on SAT

And yet another awful example of Wenger's lack of judgement: Waits for the disaster to happen and then decides to get off his backside and do something about it, and at what point was the balance tipped...4-2...5-2...6-2 or maybe at 7-2 he might have said, don't panic.....laughable..!

We are moving into the same cycle of buying foreign players who must still adapt to the EPL. I can't see these signings making any difference. We need to make English players the backbone of the squad and unfortunately our Scrooge is not willing to pay up. WENGER, I see that you are busy writing your own demise. Not convinced at all.

Could someone please answer this: why did Arsenal wait until the last 72 hours of the closing of the transfer window to make these signings? Everyone, and I mean EVERYONE in the footballing world knew what type of players Arsenal needed. WHY DID IT TAKE SO LONG? And Cahill, Jagielka, Samba, Enrique too expensive? Well Mr. Wenger, beggars can't be choosers. When you are in desperate need of a particular item, the cost becomes secondary. Who is making these decisions? Why is Arsenal panic-buying? Too many poor quality players, extraordinarily poor transfer management, poorly-timed price increases and angry fans. IMHO, indications of serious structural problems in Arsenal's management. Major damage has been done. These signings may be too little, too late.

Mertesacker will do just fine in the EPL. He already has the experience of beating EPL players in Germany's 4-1 win angainst England.

If I knew how to start a petition to get Dein back at Arsenal I would do it .... I don't think it would make a blind bit of difference but at least then the fans would have their voices heard (outside of the 'Arsenal Supporter Trust' who, to be frank, I don't trust.....) Anybody any ideas? I'm not on Twitbook of Facer so can't use them.....

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