Fulham visit Stamford Bridge for another London derby in the Premier League on Saturday.
Fulham have only suffered defeat in one of their last 10 Premier League away matches, although they have won just two in the same period. The bulk of their issues have come at Craven Cottage this season.
Goal-shy Fulham could see any faint hopes of survival further dashed in the capital, only a couple of weeks after an equally crushing afternoon at the Emirates.
VAR controversy aside, Fulham weathered the Arsenal storm and a disallowed Dani Ceballos goal before managing to break the deadlock at the Emirates, and they appeared destined to come away with three points in the bag after Josh Maja's penalty.
The Gunners' toothless attack did not seem to have any answers to Fulham's defensive solidity, but in the seventh and final minute of injury time, substitute Eddie Nketiah was on hand to bundle home at the back post and leave a disheartened Fulham ruing what could have been.
Parker's side did at least manage to snap a four-game losing run in the capital, but their hopes of a great escape are looking more improbable by the week, and the 18th-placed Cottagers are now seven points adrift of safety with five games left to play.
Chelsea will be aiming to cement their position in the top four of the Premier League table with the second-best defensive tally behind Manchester City, shipping just 31 goals all season.
The Blues head into this tie following a 1-1 draw with Real Madrid in the Champions League, while Scott Parker's side were denied all three points against Arsenal in heartbreaking fashion.
If anyone was going to stop Chelsea from taking a semi-final first-leg advantage back to Stamford Bridge, it was always going to be Champions League veteran Karim Benzema, who steered level with Raul on 71 goals in Europe's elite tournament with Real's equaliser on the night.
Christian Pulisic's well-taken goal had given Chelsea a deserved lead at the Estadio Alfredo Di Stefano, and while Thomas Tuchel may have been frustrated to only settle for a draw, the Blues have a precious away goal to take into next week's second leg.
Saturday's game represents Chelsea's second London derby in the same number of gameweeks after a Timo Werner strike propelled them to a 1-0 win over West Ham United - one which saw them open up a three-point gap on their top-four rivals with five games left to play, and the Blues are in no position to relinquish their grip on fourth spot now.
For all of their successful endeavours away from home, Chelsea have not quite been able to hack it on home soil recently, as they have won just one of their last four league games at Stamford Bridge and were held to a goalless draw by Brighton & Hove Albion on April 20.
A Mason Mount winner saw Chelsea emerge victorious in a 1-0 win at Craven Cottage earlier in the season, and the Blues have not lost at home to the Cottagers since October 1979 - a run of 18 matches without defeat against their London rivals.
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Chelsea are unbeaten in 18 home games with Fulham in all competitions since a second tier defeat in October 1979 (W10, D8).
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Fulham's solitary victory in the past 39 meetings was by 1-0 in the Premier League at Craven Cottage in March 2006 (D14, L24).
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Fulham haven't won a top-flight London derby in 23 attempts since beating West Ham 2-1 in January 2014 (D5, L18).
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The Cottagers have taken just one point from five games since their 1-0 victory over Liverpool in March.
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They've also dropped 13 points from winning positions in away fixtures this season, the worst record in the division.
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Scott Parker's first game in charge of Fulham was a 2-1 defeat by Chelsea at Craven Cottage in March 2019.
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Chelsea have lost just one of their 14 Premier League games under Thomas Tuchel, which was a home thrashing by West Bromwich Albion (W8, D5).
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Tuchel has amassed 29 points in those 14 matches, the same total Frank Lampard managed in 19 league fixtures this season before he was sacked.
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The Blues boast the best record in London derbies this season, winning six of eight and only losing once.
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Chelsea goalkeeper Edouard Mendy has kept 15 clean sheets in 27 Premier League appearances, second only to Ederson's 17 shut outs this season.