London - It took 19 games for Maurizio Sarri to suffer defeat as Chelsea manager, but a stunning start to life at Stamford Bridge has quickly turned sour with the Italian lambasting his side's mental fortitude after Saturday's 2-0 defeat at Arsenal.

A fourth loss in 11 league games leaves Chelsea at serious risk of missing out on the Champions League for a second consecutive season for the first time since Roman Abramovich bought the club in 2003.

Sarri's men are still in pole position for a top-four finish, but now lead Arsenal and a resurgent Manchester United by just three points.

Moreover, Chelsea still have to visit United, as well as title-chasing Liverpool and Manchester City in their final 15 games of the league campaign.

The trend since the Blues lost for the first time under Sarri at Tottenham at the end of November suggests Chelsea will not maintain their slender advantage.

Under Abramovich, Chelsea managers don't tend to be given time if unsuccessful in their first season.

Sarri insisted he is still up for the fight, even if he accused his players of lacking the same heart.

"It seems to me that, as a group of players, they're not aggressive from a mental point of view. They don't have a ferocity in their mentality," said Sarri.

"It's difficult to change. You have to try and influence their mentality and it could take some time, or it could change with a new player coming in or an older head assuming more responsibility and driving the team on."

Sarri does seem set to get what he wanted in the signing of Gonzalo Higuain on loan from Juventus for the rest of the season to offer some much needed firepower.

However, while the former Napoli boss pointed the finger at his players, his tactics have also come under the spotlight in recent weeks.

Chelsea's early-season form owed much to the goals of Eden Hazard with Sarri claiming the Belgian was capable of scoring 40 this campaign.

Instead, Hazard has just 12 as his goals have dried up since he has been wedged into a centre-forward role due to Sarri's lack of faith in Alvaro Morata and Olivier Giroud.

In keeping with their performances of late, Chelsea enjoyed 64 percent possession against Arsenal but had just one tame shot on target to show for it.

Removing Hazard from his favoured position wide on the left of a front three has made it easier to crowd out Chelsea's most dangerous player.

Meanwhile, as Sarri demands more aggression, his most tenacious player, N'Golo Kante, is also out of position.

Kante shone in winning back-to-back Premier League titles with Leicester and in his first season at Chelsea, as well winning the World Cup with France, as a relentless holding midfielder.

However, Sarri prefers the passing of Jorginho, who he brought with him from Napoli last summer, at the base of his midfield and Kante shunted further forward.

Hazard has voiced his frustration at playing out of position and keeping him happy is a club priority as he enters the final 18 months of his contract, with Real Madrid interested in a cut-price swoop come the summer.

Teenager Callum Hudson-Odoi also seems set to snub the offer of a new deal to join Bayern Munich after becoming frustrated at his lack of first-team opportunities under Sarri.

The Italian needs to find answers quickly to arrest Chelsea's slump with the finance and prestige of Champions League football paramount to his and Chelsea's future.

Arsenal boss Unai Emery recently revealed the financial restrictions he is working under with no money available to sign players on permanent transfers this month.

Two seasons without Champions League football is part of the reason for penny pinching at the Emirates. Now Chelsea run the risk of facing a similar fate.