The summer transfer window has now begun, with rumours and speculation continuing to swirl as Manchester City eye possible reinforcements.

The 2018-19 champions did not bring in a single player during the January transfer window, despite suffering a defensive shortage for much of the 2019-20 campaign, but they have already started their business for the summer.

Here, Sports Mole rounds up the latest news on possible comings and goings at the Etihad.

Sunday morning's Manchester City transfer talk news roundup:

Partizan confirm Filip Stevanovic talks with Manchester United

Partizan vice president Vladimir Vuletic has confirmed that his club are in talks with Manchester United over teenage attacker Filip Stevanovic.

A report on Friday claimed that United had agreed a €12m (£10.8m) deal for the 17-year-old, who scored nine times and registered three assists in 35 appearances at club level during the 2019-20 campaign.

When questioned on the speculation, Vuletic told Buta Sport: "The negotiations are ongoing."

Stevanovic, who appeared twice against United in the group stages of this season's Europa League, has previously been linked with Liverpool, Manchester City, Chelsea, Bayern Munich and Real Madrid.

The teenager would reportedly spend another 12 months on loan with Partizan before officially arriving next summer if the proposed deal were to go through.

Stevanovic has scored nine times and contributed four assists in 42 outings for his Serbian club.

Report: Manchester City to increase Kalidou Koulibaly offer to £72m

Manchester City are to step up their interest in Napoli defender Kalidou Koulibaly by tabling an improved second offer, according to a report.

The Citizens are believed to have already had an opening bid of £58m knocked back for the in-demand Senegal international.

Koulibaly has long been linked with a move away from Napoli, with Manchester United, Arsenal and Barcelona all being credited with an interest over the past 12 months.

Napoli are now ready to cash in but only if an interested party meets the 29-year-old's price tag, which is around the £72m mark.

Transfer expert Alfredo Pedulla claims that City will table their increased bid when their campaign officially ends.

Pep Guardiola has already strengthened his backline ahead of the 2020-21 campaign with the signing of Nathan Ake from Bournemouth.

More transfer news from Manchester City:

Manchester City 'in pole position to sign Lionel Messi'
Manchester City feel that they are 'in pole position' to sign Lionel Messi from Barcelona, according to a report. Read more.

Leeds United 'eye deal for £36m-rated Florentino Luis'
Leeds United could move for Benfica midfielder Florentino Luis this summer, according to a report. Read more.