Barcelona's busy January transfer window might only get tougher after reports of the club looking to add another player to their roster emerged.The Blaugrana have already signed Ferran Torres from Manchester City but haven't been able to register him in the squad yet due to La Liga's wage rules.However, Samuel Umtiti agreed to sign a new contract after taking a significant pay cut, facilitating the Spaniard's registration.Philippe Coutinho was also offloaded to Aston Villa on loan for the rest of the season with an option for the Premier League club to buy him permanently.B/R Football@brfootballBarcelona announce they have renewed Samuel Umtiti’s contract until 2026 with the defender agreeing to reduce his overall salary.It means Ferran Torres can now be registered 🤝5:12 AM · Jan 10, 2022167571054Barcelona announce they have renewed Samuel Umtiti’s contract until 2026 with the defender agreeing to reduce his overall salary.It means Ferran Torres can now be registered 🤝 https://t.co/kki9bd0t0jNow there are reports emerging from Italy that Barcelona are in the hunt for a new centre-back, with Gerard Pique past his best and Umtiti highly injury-prone.Ajax's rising star Lisandro Martinez has been touted as their main target, with the Spanish giants even readying a bid, according to Goal.The Argentine joined de Godenzonen in 2019 from local side Defensa y Justica and has been a mainstay at the heart of their backline ever since.He's made 107 appearances for the Dutch side so far, even contributing 12 goals (6G, 6A).Barça Buzz@Barca_Buzz (LISANDRO): Not only do Barcelona want to sign a top striker in the summer, they are also looking for a new centre-back for next season.• The operation to sign Lisandro Martinez can be reactivated. Xavi likes him for his intensity and ball playing.Via (🟠): @giaco_iaco11:39 AM · Jan 9, 202295743🔄 (LISANDRO): Not only do Barcelona want to sign a top striker in the summer, they are also looking for a new centre-back for next season.• The operation to sign Lisandro Martinez can be reactivated. Xavi likes him for his intensity and ball playing.Via (🟠): @giaco_iaco https://t.co/CcUSYFZaV0His meteoric rise to stardom has alerted many top sides around Europe, with Barcelona supposedly in the driver's seat.Head coach Xavi is keen to land the star at the earliest but Joan Laporta is happy to wait until summer to bring him to Camp Nou.It's also worth noting that Martinez signed a contract until 2025 with Ajax last year, meaning the club might demand a hefty fee for the player should the club officially launch a bid.Barcelona are looking to shore up their defenseBarcelona's defense this season has been poor to say the least. With 23 goals conceded in 20 league games, the club's title chances have been severely affected due to lapses at the back. Their willingness to invest in a centre-back this month is a statement of intent and one that will surely please the fans.However, Barca are facing financial troubles right now, which could be a hindrance in their pursuits. Martinez is a talented player but Ajax won't let him go for a measly sum, in which case AC Milan's Alessio Romagnoli could also be an option. He's out of contract in the summer and could be available for free.Blaugrana, however, may have to turn their attention to short-term stop-gap signings in the meantime. They are currently 17 points off leaders Real Madrid and a point adrift of Atletico Madrid in 4th place.