Arsene Wenger says a lack of “financial power” prevented Arsenal from bolstering their defensive ranks in the January transfer window.
The Gunners were able to bring added firepower in the final third onto their books, with a club-record £55 million fee acquiring Pierre-Emerick Aubameyang from Borussia Dortmund.
Henrikh Mkhitaryan also arrived from Manchester United in a swap deal which took Alexis Sanchez in the opposite direction.
Promising Greek defender Konstantinos Mavropanos was the only addition at the back, though, and Wenger admits he is unable to compete with the likes of Manchester City and Liverpool – who spent £57m and £75m on Aymeric Laporte and Virgil van Dijk respectively – for the best in the business.
The Frenchman told reporters after facing criticism for failing to enhance a key area of his squad: "Look, defensive strengthening is a huge problem for everybody.
“Everybody looks for defenders. You could see again, you look at City, they buy again a defender. How much money did they spend on defenders in the last three years?
"We don't have the financial power of Manchester City. And the fact that they conceded half the goals we conceded is as well down to the fact that offensively they are very powerful. And they have a lot of possession in the opponent's half that we have not."
Arsenal were heavily linked with West Brom’s Jonny Evans as the window came to a close.
The former Manchester United centre-half would have added vast Premier League experience to their squad, but a late offer was knocked back by the Baggies.
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Alan Pardew admitted after the deadline passed that an offer from Arsenal had got “nowhere near” securing the Northern Ireland international, with reports suggesting that the Gunners only put £12m on the table.
With no deal done, Wenger will have to dip back into the market over the summer if he is to find the necessary additions to a defensive unit which could lose Per Mertesacker at the end of his contract.