10 most expensive left-backs of all time 

#8 Kieran Tierney - €27 million (Arsenal)

Kieran Tierney has been a revelation for Arsenal

Kieran Tierney was identified as a potential solution for Arsenal's defensive woes last year and the Scottish left-back has been largely successful in the Gunners' starting line-up. The former Celtic star has displayed incredible maturity on the pitch for Arsenal and is likely to be a fixture in the side for years to come.

Keiran Tierney cost Arsenal a considerable amount of money and did not enjoy a particularly fruitful start to his time at Arsenal. The Gunners spent €27 million to bring the left-back to the club and his shoulder injury under Unai Emery dampened the excitement surrounding his arrival.

With Mikel Arteta at the helm, however, Tierney has become a virtually irreplaceable part of the Arsenal side and played a pivotal role in the Gunners' FA Cup victory. Arsenal have become a resilient side under Arteta and Tierney's presence in the back-line has become a blessing for the club.

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#7 Leonardo Spinazzola - €29.5 million (AS Roma)

Leonardo Spinazzola was touted as a prodigy

Leonardo Spinazzola was considered one of the most promising left-backs in Europe at the start of the decade and was drafted into the Juventus youth set-up as a teenager. The Italian full-back spent several loan spells across the country before securing a permanent transfer to AS Roma for a €29.5-million fee in 2019.

The left-back has endured several injuries at the Stadio Olimpico and has been fairly inconsistent with the Giallorossi. Spinazzola has managed to secure a permanent spot in the starting eleven, however, and is often played as a wing-back in Paulo Fonseca's 3-5-2 formation.

Official: Leonardo Spinazzola is now a Roma player. This summer #ASRoma will use each transfer announcement video on social media to help raise awareness about the search for missing children globally. @MissingKids ❤️ @telefonoazzurro pic.twitter.com/sy9GheDhsg

— AS Roma English (@ASRomaEN) June 30, 2019

With AS Roma showing plenty of promise over the past year, Leonardo Spinazzola may well justify his price tag this year and guide the Giallorossi back to the Champions League.

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#6 Fabio Coentrao - €30 million (Real Madrid)

Fabio Coentrao spent a few years at Real Madrid

Fabio Coentrao joined Real Madrid in 2011 and spent seven years with the Spanish giants. The Portuguese left-back did cost the club €30 million but did well in his first few years under Jose Mourinho.

Coentrao served as a viable back-up option to Marcelo for Real Madrid and also made a few appearances in the midfield for Los Blancos. The full-back's performances dropped under Carlo Ancelotti and he eventually fell out of favour at the club.

The left-back secured a move back to his boyhood club Rio Ave in 2018 and spent two years at the club. Coentrao announced his retirement for professional football earlier this year.

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#5 Sergio Reguilon - €30.5 million (Tottenham Hotspur)

Sergio Reguilon has joined Tottenham Hotspur

Sergio Reguilon was a revelation last season with Sevilla and was exceptional in the Spanish side's successful Europa League campaign. The former Real Madrid left-back was snapped up by Jose Mourinho's Tottenham Hotspur in the transfer window last month.

The Spurs paid in excess of €30 million for Sergio Reguilon and given the current financial climate in European football, the Spanish left-back has plenty of work to do to justify his price tag.

Sergio Reguilon smashing the traditional new boy sing a song initiation. Spurs' new left-back is certainly a confident young man. pic.twitter.com/bLYpdze5g7

— Alasdair Gold (@AlasdairGold) September 26, 2020

Reguilon is likely to take Ben Davies' place in Tottenham's line-up in the coming months and will have to work hard to earn Jose Mourinho's favour. The left-back is a prodigious talent and can become an excellent player in the Premier League.

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