Jose Mourinho makes his second return to west London since being sacked by the Blues, and will hope it goes better than his first.
Chelsea's pursuit of the double in Antonio Conte's debut season at Stamford Bridge finds a familiar face standing in its way on Monday night.
The Blues' quarter-final clash with Manchester United sees Jose Mourinho hoping to ruin his former club's hopes of a league and cup double.
The Portuguese has already claimed the opening domestic trophies of the season (Community Shield, League Cup) to get his tenure at Old Trafford off to a winning start.
But his hopes of landing another domestic trophy have been seriously dented by top scorer Zlatan Ibrahimovic's suspension.
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United and their manager are searching for revenge in west London, having been thumped 4-0 by Conte's Premier League leaders earlier in the season. To stand any hope of achieving it, they're going to need to be at their best.
Here are six key questions ahead of the FA Cup quarter-final clash:
1. Can United stop Eden Hazard?
The Belgian was charged as one of the 'rats' who packed up their tools and left Jose Mourinho to sail up the proverbial creek without a paddle last season.
But Hazard is back looking like the man who won Player of the Year in 2014-15 under Conte, and looks set to be in the reckoning when the awards are dished out in the next few months.
The No.10 has been nothing short of outstanding, thriving in a free role behind Diego Costa, which frees him of defensive obligations and makes him the Blues go-to guy when they hit on the counter (just ask West Ham).
Now 26, Hazard already has a host of medals under his belt, including league titles, domestic cups and player of the year crowns in both England and France. But what he doesn't have in his fast growing collection is an FA Cup winners' medal, something he desperately craves.
So can Mourinho stop him? Antonio Valencia is expected to play at rightback, while United will likely will go with a tight three-man midfield, trying to cut down the space in which Hazard and Pedro can roam. Certainly, the form the Belgium skipper is in, it's going to be a very difficult task.
2. How does Jose Mourinho deal without Zlatan?
It's an understatement to declare Manchester United have relied heavily on Zlatan Ibrahimovic this season.
At times the veteran Swede has been a one man tour de force in attack, scoring 26 goals in all competitions and laying on eight more.
But suspension means Mourinho's men are shorn of their leading marksman, leaving the Special One with a big decision to make.
If that wasn't bad enough, he could also be without Wayne Rooney, Anthony Martial and Marcus Rashford, who were all absent when the squad travelled down to London on Sunday night.
Henrikh Mkhitaryan or Marouane Fellaini will spearhead United's attack at Stamford Bridge.
3. Which Frenchman takes charge in midfield?
N'Golo Kante's rise to become arguably the Premier League's most important player has been wholly unexpected.
His rise in the last 20 months, since joining Leicester from the modest French side Caen, has been both surprising and refreshing. All action, he makes tackles, interceptions, passes well and covers so much of the pitch that Hazard isn't the first to joke it's like playing 'with the Kante twins'.
So often this season he has set the tone for Conte's side, with the Italian citing him as "an example to all". Tonight, Chelsea will again look to him to win the midfield battle.
Opposite Kante will be his compatriot, more fêted, a teenage phenom, someone who, even at 23, the football world has known about for almost a decade: the world's most expensive player, Paul Pogba.
Athletic, intelligent, technically magnificent, the ex-Juventus man is very much the prototype of a modern midfielder. Some argue he has been inconsistent this term, but at his age, that is to be expected.
At times he has shown why United spent so heavily to bring him back to Old Trafford and if he is to fully justify his price tag, it is games like this when he needs to take charge and dominate.
He can't just be window dressing, he needs to grab the game by the scruff of the neck. The problem will be when Kante comes ratting at his heels - will Pogba shrug him off?
4. Conte's cup conundrum with skipper Terry
It's something John Terry has had to get used to this season, the Blues skipper being forced since the switch to a back three to watch Cesar Azpilicueta, David Luiz and Gary Cahill cement themselves as Conte's preferred centre-half threesome.
But in the FA Cup, Terry has at least been offered some light relief. The 36-year-old has started all three of Chelsea's matches in the competition so far, the wins over Peterborough (against whom he was also sent off), Brentford and Wolves.
It will be interesting to see how Conte plays it against a fellow Premier League side. He's already said there will be no special treatment for Terry in this cup run, and that players will only play on merit.
5. Will rest periods play a part?
Antonio Conte's side will have enjoyed seven days rest ahead of the meeting, having last been in action against West Ham last Monday night.
Since then, United have been to Russia and back, with their Europa League trip to Rostov putting them in pole position to make the last eight of that competition.
United will no doubt be thankful this game has been moved tonight, allowing them an extra 24 hours rest time.
But while Chelsea's preparation has been idyllic, the travel and state of the Moscow pitch has ensured United's has been anything but.
6. Will we see touchline antics?
Jose Mourinho accused the current Blues boss of trying to humiliate him with his actions after N'Golo Kante's fourth goal in the crushing Premier League defeat in October.
Mourinho had a word in the Italian's ear, and the bad feeling spread to the tunnel as United's coaching staff snubbed the Italian's handshake in the tunnel.
Conte has stated clearly that he will not tone down the touchline celebrations and histrionics, which have so delighted Stamford Bridge this term.
Mourinho himself is prone to the odd run down the touchline to celebrate a winning goal and there was more than a hint of irony when he recently accused his former club of playing boring, defensive football.