Chelsea defender Gary Cahill admits his side's crunch clash with Manchester City on Monday will be the ultimate test of their Premier League title credentials.
City swept to the top of the table with a 5-1 demolition of Tottenham in midweek, while Chelsea lost ground in the title race after being held to a frustrating goalless draw at home to West Ham.
Jose Mourinho's third-placed team trail leaders City by three points and a defeat at Eastlands would be a major blow to Chelsea's hopes of winning the English crown for the first time since 2010.
Mourinho accused West Ham of playing "football from the 19th century" after the east Londoners settled for a cautious approach in midweek, but City's dazzling array of attacking talent may force the Chelsea boss to adopt a conservative gameplan himself.
The Blues have already beaten Manuel Pellegrini's side this season when a Joe Hart error allowed Fernando Torres to a score a late winner at Stamford Bridge in October.
But City have been in majestic form since then and their five-star display at White Hart Lane extended their unbeaten run to 20 matches in all competitions.
Pellegrini's men have scored a remarkable 115 goals this season and they have been invincible at Eastlands, crushing all opposition to record a 100 per cent record of 11 wins on home turf in the Premier League.
Even the country's best teams have been embarrassed at Eastlands, with Manchester United conceding four and Arsenal and Tottenham both hit for six.
England international Cahill acknowledges Chelsea, who will move level on points with City if they win, will have to produce their very best to emerge from Eastlands undefeated. "They're banging goals in left, right and centre. It's going to be really tough," Cahill said.
"We had a really good result against them at our place but at home they've been so strong. I suppose it's the ultimate test. It's going to be a really, really tough game."
If City striker Sergio Aguero fails to recover from a hamstring injury, Pellegrini will choose between Alvaro Negredo or Stevan Jovetic as his replacement.
Jovetic replaced Aguero at Tottenham and notched his first Premier League goal since his £22 million transfer from Fiorentina last year.
The Montenegro forward, who is finally fit after battling injury and illness, warned his team-mates to guard against over-inflated expectations after a host of pundits this week labelled them champions elect. "We were really happy after beating Tottenham but we need to stay calm because nothing is finished," Jovetic said.
"The next one against Chelsea is going to be a crucial game. I hope we will play like we did against Tottenham. At the moment, everything is perfect but we need to do our job as we did until now and like this we can be successful."
Misfiring Gunners seek rebound
Second placed Arsenal, who host Crystal Palace on Sunday, can't afford another slip after falling one point behind City following a 2-2 draw at Southampton.
With City and Chelsea not playing until Monday, the Gunners would temporarily regain first place if they beat Palace.
"We have to look at ourselves and only think we have to move forward," Arsenal manager Arsene Wenger said. "The kind of performance we delivered at Southampton will not move us forward, so let's focus to come back on Sunday and produce a good performance."
Manchester United travel to Stoke looking to close the gap on fourth placed Liverpool in the race to qualify for the UEFA Champions League.
United defeated Cardiff in midweek to mark the debut of £37 million club record signing Juan Mata.
And the Spanish midfielder has already made a good impression on his new team-mates, according to United winger Ashley Young. "Juan looked like he had been here for years," he said.
"He had only been training for two days and it was his first game but he has gelled straight away. When he has fully settled in he will add something special to the squad."
Newcastle host Sunderland in the highly-charged Tyne-Wear derby, while fourth placed Liverpool travel to West Brom aiming to build on their 4-0 thrashing of Merseyside rivals Everton.
English Premier League fixtures
Cardiff v Norwich
Everton v Aston Villa
Fulham v Southampton
Hull v Tottenham
Newcastle v Sunderland
Stoke v Manchester United
West Ham v Swansea
Arsenal v Crystal Palace
West Brom v Liverpool
Manchester City v Chelsea