Full-backs require Pep Guardiola's full attention at Manchester City

Dani Alves looks likely to be the latest part of Pep Guardiola's Manchester City summer transfer splurge and the first of a major overhaul of his defence. Portuguese playmaker Bernardo Silva was the first arrival, adding more creativity, and was quickly followed by Ederson Moraes to sort out City's goalkeeper problems.

But while there are likely to be more signings to add options elsewhere in his team, Guardiola has now turned his attention to the defence, an area many saw as City's biggest problem last season as they failed to compete for silverware.

The City boss is short of full-backs after allowing veterans Pablo Zabaleta, Bacary Sagna and Gael Clichy to leave on a free when their contracts expired at the end of the season. Aleksander Kolarov, who will be in the final year of his contract, was used predominantly as a left-sided central defender, which means Guardiola could potentially need to sign four new full-backs.

He is desperate for players with the energy to supplement attacks as well as defend, and none of those four were seen as good enough.

"We don't have full-backs to go up and down, up and down, because all of them are 33, 34 years old, so I adapt with the quality of players," Guardiola said after the 0-0 draw with Manchester United in April. "We attack a lot with the full-back, but Pablo, Sagna, Kolarov and Clichy -- all of them they are more than 33 years old and they don't have the legs to go up and down."

At 34, Alves is no longer at his peak, though he remains a quality player and can step straight into Guardiola's side knowing exactly what is required. But even at his best during his Barcelona days under Guardiola, the Brazilian defender would have struggled to cope with the demands of the Premier League on top of the Champions League, which is why the Catalan coach wants a second quality right-back so he can rotate throughout the season.

Tottenham Hotspur's Kyle Walker has been identified as a top target and would seem a good fit for Guardiola's requirements, although an agreement has not yet been reached, with Spurs asking around £45m.

Guardiola has spoken of wanting to build his team around a core of homegrown players and signing the current England right-back would be the perfect starting point. Walker, who has matured under the guidance of Mauricio Pochettino at Spurs, could be an ideal player to rotate with as he possesses a similar mix of speed and stamina to Alves and could finesse his game even further at the Etihad Stadium.

Guardiola is looking for similar players on the left and could potentially sign two more highly rated full-backs in Monaco's Benjamin Mendy and Southampton's Ryan Bertrand. Mendy, 22, is one of the most exciting young full-backs in Europe and has all those attacking and fitness qualities the City boss wants.

Bertrand, meanwhile, has been one of the most reliable full-backs in the Premier League since he moved to Southampton and is only behind Danny Rose -- another potential target -- in the England pecking order.

With those deals potentially close, Guardiola will then switch his attention to the centre of defence, which is a more complicated issue with seemingly no spaces currently in his squad.

City spent £47.5 million on England defender John Stones last summer, and while the 23-year-old had a mixed first season at the Etihad, Guardiola sees him as a long-term prospect. The Catalan coach is happy with Stones' progress and ability to play out from the back, saying in March that: "John Stones has more balls than everyone here."

Guardiola has also said he is pleased with the contribution of Kolarov, while Nicolas Otamendi made more appearances than any other central defender at the club last season. City were further boosted by the return of captain Vincent Kompany, who put two years of injury problems behind him in an impressive end to the season, anchoring the defence.

With youngster Tosin Adarabioyo signing a new, four-year contract and desperate for an opportunity, there's currently no room for new players. Otamendi could be the most likely to leave after flirting with a move to Spanish giants Real Madrid and Barcelona, although it's unclear if either club are actually interested.

Guardiola is a huge admirer of Juventus defender Leonardo Bonucci and he would be the perfect fit for his defence. But, after turning 30 and with the Italian champions putting a price tag on him of around £50m, he could be an option that City ultimately decide to pass on with so many other new additions to his back-four.