Sidnei is said to be on his way to Barcelona. Getty

Barcelona are on the verge of completing the signing of Deportivo de la Coruna centre-back Sidnei, according to reports in Spanish media. AS claims the Brazilian defender has already reached an agreement in principle to become the Catalans' first signing of the summer, kicking off the long-predicted overhaul of Luis Enrique's back-line.

The reigning La Liga and Copa del Rey champions currently have five established centre-backs on their books: Gerard Pique, the versatile Javier Mascherano, Jeremy Mathieu, Thomas Vermaelen and Marc Bartra. However, Bartra is expected to leave the Nou Camp in the coming mercato having fallen out of favour with Luis Enrique, while the club have publicly admitted they are after a new player to partner Pique in the heart of defence as the other three players are already the wrong side of 30.

Mascherano has been a vital player for Barcelona since dropping back from midfield, but reports in Spain suggest he is considering his future at the club, with both Juventus and an unnamed Chinese outfit after his services.

Vermaelen is also tipped to leave in the upcoming window, having suffered an injury-ravaged two seasons since moving from Arsenal in the summer of 2014. Sport recently claimed Liverpool had launched a cut-price offer to bring the player back to the Premier League. However, Barcelona are believed to be holding off until after the European Championship, hoping Vermaelen's performances with Belgium will up his market value.

Barcelona have accordingly been linked with a number of world-class centre-backs in recent months, including Athetic Club's Aymeric Laporte, Atletico Madrid's Jose Maria Gimenez and Paris Saint-Germain star Marquinos.

But AS claims that the club have opted for a much more low-key option in Sidnei.

The Spanish publication says the former Benfica defender turned down an offer to remain at Riazor to move to the La Liga giants. It adds that the 26-year-old has reached an agreement in principle, adding that Sidnei may already be in Barcelona to undergo a medical ahead of the move.

Sidnei has been a mainstay for Deportivo during the last two campaigns, moving on loan from Benfica before the Galicians acquired his services on a permanent deal. The Brazilian also knows Catalonia well, having spent the 2013-14 campaign at Espanyol, making 18 appearances for Barcelona's neighbours.

The player's signing does not necessarily mean the end of Barcelona's defensive hunt, as the departure of Mascherano, Bartra and Vermaelen would necessitate further reinforcements. Although the club are in negotiation with Las Palmas to sign the young Mauricio Lemos, it is believed they will send him on loan immediately to continue his development.