Manchester City Transfer News: Latest Rumours on Sergio Aguero and Aaron Martin

Sergio Aguero is reportedly a transfer target for La Liga giants Real Madrid. Aguero is said to be Los Blancos' top choice for the January window.

French source Le10 Sport (h/t TalkSport.com) reported Los Merengues' interest. However, TalkSport noted how the Manchester club is "expected to be very reluctant to let Aguero leave for any price."

It would make sense for City to resist any interest from Spain in their main striker and record goalscorer. Aguero recently took his place as City's all-time leading goalscorer after netting for the 178th time during City's 4-2 win over Napoli in the UEFA Champions League.

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The Argentinian added to his landmark tally by rolling in a penalty during Sunday's 3-1 win over Arsenal in the Premier League. Beating the Gunners put City eight points clear in England's top flight.

Aguero is a major reason why City are setting the pace in the title race. He has scored eight times and provided three assists in the league, per WhoScored.com.

No player has been more prolific in the Premier League than Aguero since he joined City from Atletico Madrid, according to Sky Sports Statto:

As good as he's been, Aguero hasn't always found things easy under City manager Pep Guardiola. Aguero was dropped for a fifth time last season back in February, per James Robson of the Manchester Evening News.

Guardiola also relegated Aguero to the bench against Bournemouth earlier this season, per Stuart Brennan of the Manchester Evening News. City are no longer as reliant on Aguero as in years past, not since Gabriel Jesus joined the club in January.

The Brazilian has given Guardiola's squad another prolific marksman, one who has made a habit of scoring in the league, according to BBC's Match of the Day:

Jesus has said he doesn't mind playing a backup role to Aguero, per Jeremy Cross of the Daily Star. Having both Aguero and Jesus to call on means City boast the best strike pairing in the league.

Guardiola has been able to play them both together or rely on one to lead the line. Such tactical flexibility means Aguero is too important for City to let go in January, no matter how much money Los Blancos were to offer.

City have depth at striker but lack a similar quality at left-back. It's why the club remains keen on Espanyol's Aaron Martin, per Simon Jones of MailOnline.

Jones noted how City considered signing Martin in the summer as they became embroiled in protracted negotiations with AS Monaco for Benjamin Mendy. City eventually signed Mendy, but the France international is out for the season with a knee injury.

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The Manchester club has kept up its interest in Martin, per Jones: "City have had scouts at a number of Espanyol games this season with Spain Under 21 international Martin also drawing attention from other clubs including Manchester United."

The report also reveals how City may bid in January for the defender who has a release clause valued at £35.5 million.

Signing Martin would be a good move since City have been relying on converted midfielder Fabian Delph in the role since Mendy suffered his injury. Danilo can also play on the left but is better suited as a right-back.

Signing a burgeoning young talent like Martin would ensure City have the cover they currently lack at left-back. Keeping Aguero will ensure Guardiola's squad remains the most free-scoring in England's top flight.