Chelsea Transfer News: Latest on Diego Costa and Nicolas N'Koulou Rumours

Turkish side Galatasaray are reportedly preparing to offer Diego Costa a sensational escape from Chelsea in January following the striker's struggles this season.

According to Turkish outlet Fotomac (h/t James Gray of the Express), Galatasaray "are planning on offering Chelsea the chance to offload the struggling striker, even if it is only on a loan basis."

As Sky Sports News HQ revealed prior to the Blues' 1-0 home defeat to Bournemouth on Saturday, Costa fell well short of the standards he set last season:

The Spain international hit the headlines repeatedly last season for his aggressive approach to the game, and thanks to his frequent failure to get on the scoresheet in this campaign his behaviour is arguably subject to even more scrutiny.

Football writer Henry Winter described his antics in September's game with Arsenal, for which he was retrospectively hit with a three-match ban for being "an embarrassment":

The Blues aren't likely to part with him just yet, though, particularly in January, as they are already lacking in quality alternatives to him anyway—even if they brought in another forward to replace him, they would still be short a centre-forward.

Further, as Gray notes, despite his downturn in form Turkey represents a serious step down from the Premier League, one that Costa isn't likely to take at just 27.

As well as up front, Chelsea could also do with recruiting defensively, having conceded a staggering 24 goals in the Premier League this season.

ANNE-CHRISTINE POUJOULAT/Getty Images

One such option is Marseille centre-back Nicolas N'Koulou, who according to Foot 365 (h/t Charlie Phillippe of the Express) will be the subject of a battle between the Blues, Liverpool and Fiorentina in the summer as his contract "expires at the end of the current season and he is unwilling to extend his deal with the club."

As OptaJean demonstrated, the 25-year-old has been a key figure for the Ligue 1 side and was sorely missed during a spell out with injury last season:

Further, the Cameroonian compares well with Everton centre-back John Stones, a reported transfer target for Chelsea last summer, per WhoScored.com:

With captain John Terry soon turning 35, Chelsea's need for reinforcement at centre-back is even more pressing as his days at the club are surely numbered.

N'Koulou represents an outstanding option for the Blues to pursue, doubly so given that it seems he will be available for free in the summer.

Stones is also an exceptional candidate and has four years on N'Koulou, but with him proving difficult to prise away from Everton and likely to break the bank of any team who capture him, the Marseille man makes an excellent alternative.