Matthijs de Ligt
Matthijs de Ligt only signed a new deal until 2021 at Ajax in the summer. Getty

Ajax starlet Matthijs de Ligt is said to have emerged as the top Barcelona target to bolster Ernesto Valverde's back-line ahead of the 2018-19 campaign.

Mundo Deportivo says the Catalan giants have focused their attention on the 18-year-old centre-back because a more experienced alternative would set them back a significantly higher sum.

The Spanish publication has been reporting for a while that Valverde has earmarked the signing of a centre-back as his top priority ahead for the next summer transfer window.

Barcelona are tipped to trigger a €9m (£8m) first refusal clause for Colombian international Yerry Mina either in January or in the summer, but the boss still wants another defender to provide competition for Gerard Pique and Samuel Umtiti at the heart of the back-line.

Both 33-year-old Javier Mascherano and 31-year-old Thomas Vermaelen have suggested in recent days that they could leave the Nou Camp, with the latter yet to play a single minute this term.

Earlier this week Mundo Deportivo reported that Barcelona are monitoring Napoli star Kalidou Koulibaly as the 26-year-old centre-back would suit the Catalans' passing game.

However, Barcelona know they would need to spend at least €60m to lure him away from Napoli, and are thus looking for a more affordable alternative.

This explains why Ajax's De Ligt has been identified as their new number one target in defence.

Mundo Deportivo says Barcelona also like 18-year-old Dayout Upamecano, but the French starlet is very much seen as the second choice as they know luring him away from RB Leipzig will be much more difficult.

De Ligt, however, appears to tick all the boxes to join Barcelona in the summer.

Even though he is only 18, the Dutchman has already established himself as an unmovable starter at Ajax and is also a regular in the Netherlands national team.

The young defender only signed a new deal at Ajax in the summer but Mundo Deportivo believes that this shouldn't affect a potential deal as the Eredivisie side are a selling club.

The report adds that Barcelona could face competition to secure his services as former Ajax boss Peter Bosz is also keen on a reunion at Borussia Dortmund.

Mundo Deportivo thus suggests that Barcelona could bring the move forward to the upcoming January transfer window in order to avoid more clubs joining the battle in the summer. If this was the case, the Catalans would need to decide whether to keep him on loan at Ajax until the end of the season or bringing him straight away to begin his adaptation to Valverde's style.

One way or another it looks clear that Barcelona will sign a new centre-back – plus Yerry Mina – ahead of next season. Over the summer Valverde already asked club officials to bolster the position with Real Sociedad's Iñigo Martínez.

Mundo Deportivo says that a new move for the Spaniard is not totally ruled out either, with Valverde also keeping an eye on his former Athletic Club Bilbao centre-backs Yeray Álvarez and Aymeric Laporte.