Chelsea and Manchester United have entered a bidding war for £40m Monaco star Tiemoue Bakayoko... but is he worth the money?

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Having already gazumped Chelsea once to sign Romelu Lukaku last week, Jose Mourinho and Manchester United are now plotting to swoop for another Blues transfer target.

United have told Monaco they are prepared to pay in excess of £40millon for their 22-year-old midfielder Tiemoue Bakayoko.

Bakayoko is one of Chelsea manager Antonio Conte's main summer targets and the Premier League champions were confident their opening bid of £37m would be sufficient.

Chelsea and Manchester United are locked in a bidding war for £40m Tiemoue Bakayoko

Monaco star Bakayoko posted this Instagram photograph in front of a private jet

Now, United's entry into the bidding war has changed the dynamic and the ball is in Chelsea's court to match the Old Trafford club's offer for the France international.

Although a fixture in the Monaco squad since 2014, it has only been in the past year that Bakayoko has gained a wider appreciation beyond avid followers of French football.

Monaco winning their first Ligue 1 title since 2000 obviously helped, but it was Bakayoko's dynamic performances on the European stage that have promoted this intense interest from two of the Premier League heavyweights.

Bakayoko was the man who headed Monaco's winning goal in the two-leg epic against Manchester City in the Champions League last-16, while his performances also earned him a maiden national team call-up.

For Bakayoko personally, the last season was a vindication of his decision to straighten up his act and cast off the follies of his teenage years to concentrate whole-heartedly on improving his game.

As he approaches his full potential, it's easy to see why Chelsea and United are so keen on signing a player that draws inevitable comparisons to the Manchester City midfield juggernaut Yaya Toure.

The young Monaco midfielder celebrates his winning goal against Manchester City in March

The 22-year-old made 51 appearances for Monaco last season as they secured the Ligue 1 title

Bakayoko is a commanding figure having developed physically from a slender teenager and his game has come on leaps and bounds as well.

A quick and intelligent reader of the game, powerful in the tackle and capable of driving forward and selecting the correct pass, he is certainly in the Toure mould.

'If there's one player I admire, it's Yaya Toure,' said Bakayoko during his time at Rennes in 2011. 'Why? Because he has everything I would like to have in my game one day.'

Bakayoko actually has a similar background - although Paris-born (his No 14 shirt is a tribute to the Arrondissement he grew up in), he is of Ivorian heritage and was eligible for Les Elephants until making his debut for France against Spain back in March.

In truth, Bakayoko operates deeper than Toure, in a defensive midfield role shielding the back line and therefore gets himself forward less.

At Chelsea, he would be a like-for-like replacement for Nemanja Matic, who is expected to depart this summer, while at United he could be a long-term replacement for Michael Carrick.

Bakayoko takes on Juventus forward Gonzalo Higuain in the Champions League semi-finals

Bakayoko has drawn comparisons with the Manchester City midfielder Yaya Toure

His suitors certainly shouldn't expect too many goals - Bakayoko's header against City was one of three last season and six overall in his career, though at 6ft 1in he can cause damage at set-pieces.

But in a Monaco side encouraged by coach Leonardo Jardim to attack at every opportunity - they scored 107 league goals last season and 22 in Europe - Bakayoko was the ideal anchor to prevent them being overrun on the counter.

It's hard to imagine now, but Bakayoko's path to top-level football was far from straightforward.

A broken leg while a young player cost him a place at the renowned Clairefontaine Academy and by the time the bones healed, Rennes were the only club left willing to give him a chance.

Joining as a 13-year-old, Bakayoko developed his on-field attributes but let himself down with his behaviour off it. 'I did quite a few stupid things,' he admitted at 17.

This immaturity delayed his first-team breakthrough but the calming influence of Rennes coach Yannick Menu and then-manager Philippe Montanier eventually set him on the right track.

The 22-year-old enjoyed a breakthrough campaign at Monaco after initial disappointments

Bakayoko puts in a crunching tackle of Claudio Marchisio of Juventus last season

After just 28 first-team appearances for the Breton club, Bakayoko moved to Monaco in a deal worth £7m.

'He didn't really feel like leaving, but the chance was too good to refuse, both financially and professionally,' said Montanier.

For his first two seasons in the Principality, it looked as though Bakayoko had made a horrendous mistake.

Making his debut in a home fixture against Lorient, he performed terribly and was substituted by coach Jardim after only 32 minutes, causing immediate damage to their relationship that took months to repair.

A thigh injury further restricted his opportunities in a forgettable debut season, and the following campaign wasn't much better.

It was only at the beginning of last season that the penny dropped and Bakayoko completely overhauled his lifestyle.

He moved from a showy Riviera villa into a smaller apartment, repainted his pink Porsche 4x4 into a more modest black, took up boxing lessons and even consulted a dietitian.

He made his first appearance for France in their March friendly with Spain in Paris

Menu was consulted to help put him on track, while the positive influence from Claude Makelele, who joined Monaco's coaching staff, soon became apparent.

'It was hard during two years that have served a lesson to me,' reflected Bakayoko last season. 'I know how I have to behave.

'I don't regret those two years, they have shaped me. Today, I'm ready to take up any challenge.'

That transformation in attitude certainly became apparent once Jardim restored him to the Monaco side. After a successful 12 months, Bakayoko's stock has soared.

Now he will take up another challenge - but whether that will be in London or Manchester remains to be seen.