LONDON • Champions and contenders suffered title setbacks yesterday in warning signs that improvements are necessary for Chelsea, Liverpool and Arsenal.

Jose Mourinho's 100th English Premier League game at Stamford Bridge was soured by Crystal Palace's shock 2-1 victory.

It was only the Portuguese's second home defeat in that period, but already the second time this season that the champions have lost.

With Manchester City - the other team that have beaten Chelsea - maintaining their 100 per cent record with a 2-0 home win over Watford, the gap between the two sides is now eight points.

Four points from four games for Chelsea represents their worst start to a season since 1995.

Despite boasting - and retaining - the best defence of last season, the Blues have conceded nine goals this term - their worst defensive record at this stage since 1972.

Their backline again looked suspect in the second half, with Bakary Sako opening the scoring in the 65th minute. Joel Ward restored the lead nine minutes from time after Radamel Falcao netted his first goal for the Blues.

But with the summer transfer window closing on Tuesday, Mourinho has insisted that he will cope with his squad and will not ask to sign more players. "We didn't have 11 players at a normal level," he added. "We had some, not 11."

Over at Anfield, Liverpool were also punished for lapses at the back, falling 0-3 to West Ham - their first home defeat by the Hammers since 1963.

Martin Skrtel's poor headed clearance fell at the feet of Aaron Cresswell and his low cross was prodded in by Manuel Lanzini.

Slaven Bilic's team doubled their lead in the 29th minute when Mark Noble side-footed home after Reds defender Dejan Lovren carelessly allowed Lanzini to seize possession.

A dismal day for Liverpool was completed when Brazilian playmaker Philippe Coutinho was sent off for his second booking in the 56th minute. Referee Kevin Friend also sent off Noble in the closing stages for a lunging tackle, but there was still time for Diafra Sakho to complete Liverpool's embarrassment with a third goal in stoppage time.

For Arsenal, their problems are up front. The Gunners laboured to a 1-0 victory over 10-man Newcastle United yesterday and only had a Fabricio Coloccini own-goal to show for their endeavours despite racking up 21 efforts on goal.

After the 16th-minute dismissal of Aleksandar Mitrovic, Arsenal dominated possession but struggled to break down the hosts' resolute defence. In the 52nd minute, Newcastle captain Coloccini deflected Alex Oxlade-Chamberlain's goal-bound shot into his own net.

Despite the Gunners' array of dazzling attacking talent, only Olivier Giroud has netted in four matches this season - along with two own-goals in away victories at Crystal Palace and Newcastle.

In two matches at the Emirates Stadium - a surprise 0-2 opening-day defeat by West Ham and a goalless draw against Liverpool - Arsenal have failed to score despite creating chances at will.

"You always want more scorers but I believe that at the moment we have not fired on all cylinders offensively," manager Arsene Wenger told BT Sport. "Our finishing has maybe not been absolutely clinical and we have to focus on that. We have offensive potential.

"We still have (Danny) Welbeck and (Jack) Wilshere out. We did not have (Mesut) Oezil today and they are all offensive players."

REUTERS, AGENCE FRANCE-PRESSE