Man Utd skipper Maguire who was fortunate to still be on the field, having earlier appeared to kick out at Michy Batshuayi, then powered home from a Bruno Fernandes corner.
But the drama wasn't finished there, Giroud thought he had halved the deficit but again VAR came to the visitors' rescue.
CHELSEA
Key Talking Point
Where else to start, other than that three-letter word VAR?
It was a night of sheer frustration for Lampard's men as not once but twice they were denied goals courtesy of the video assistant referee, while the system failed to intervene on Maguire's off-the-ball challenge.
First Zouma's header was ruled out after Azplicueta had been adjudged to push Williams in the build-up to the goal.
But it appeared harsh, especially as the Spaniard had been initially impeded by United midfielder Fred.
Then they had the injustice of Maguire finding the back of the net after the England defender arguably should have been sent off for his earlier kick out on Batshuayi.
Substitute Giroud was the next to be denied, though there was little to complain about as his foot was clearly offside for his expertly taken header.
Nevertheless, it was another game that once again had pundits and spectators alike talking about VAR and its implications, more than the teams' performances.
Player Ratings
Starting XI:
Subs: Mount (7), Zouma (7), Giroud (7)
STAR MAN - Mateo Kovačić
The Croatian midfielder is enjoying his best season in the Blue of Chelsea and he was once again the driving force behind Lampard's men against United.
He was constantly looking to pick the ball up and make things happen for the home side.
What a game Kovacic is having so far, such a confident start to the game.
— NiiNiiFC-BlueLionsTV (@NiiNiiFC) February 17, 2020
Come on Chelsea!!!
Kovacic is causing all kinds of problems for Man United. His dribbling ability helps break the lines leading to a close effort from Willian. #CFC #CHEMUN #MUFC
— Nizaar Kinsella (@NizaarKinsella) February 17, 2020
I’ll go as far to say that Kovacic is more valuable/important to this Chelsea side than Jorginho is.
— Adam (@CFCMethod) February 17, 2020
Love having them both tho, Jorginho is class. #CFC
The midfielder was at his battling best up against Fred and Chelsea old boy Nemanja Matić in the centre of the park.
Ngolo Kanté being forced off early through injury meant a greater onus was placed on Kovačić's shoulders, a responsibility which he took in his stride.
He was denied by a wonderful last-ditch challenge by Eric Bailly as Chelsea looked to claw their way back into the game.
MANCHESTER UNITED
Key Talking Point
United probably should have been down to ten men with Maguire lucky to stay on the pitch. In a carbon copy of the Heung-min Son red card against Chelsea, tumbling to the floor Maguire seemed to petulantly kick out at Batshuayi off the ball, catching him in the groin.
#mufc a goal up but could easily be a man down. Maguire straightens leg, studs go into Batshuayi's privates. Escapes punishment. Son did same on Rudiger in December, got sent off. The vagaries of VAR. #CHEMUN
— Henry Winter (@henrywinter) February 17, 2020
Maguire is English so stray boots are a result of misguided passion not crazed malice
— Duncan Alexander (@oilysailor) February 17, 2020
Referee Antony Taylor missed the indiscretion but the decision was consulted by VAR. However, no violent conduct was decided and Maguire remained on the field.
It was, without doubt, a turning point in the game as United would have found it an uphill task had Maguire received his marching orders.
The Chelsea bench, boss Lampard and Jody Morris were up in arms by the ruling to wave play on without punishment for United's skipper.
Player Ratings
Starting XI:
Subs: Pereira (6), Ighalo (6), Dalot (N/A)
STAR MAN - Eric Bailly
After a nervy start to the game, Bailly grew into the match and gave a solid performance at the heart of United's defence.
It was expected that the defender would take a while to bed back into United's rearguard, having been out since the opening day victory against Chelsea in August.
What a performance by Eric Bailly pic.twitter.com/j1rXIZMXzb
— Calum Acton (@MUFC_Acton) February 17, 2020
Eric Bailly dropping his shoulder in his own 6 yard box under some serious pressure. What a guy.
— The Man Utd Way (@TheManUtdWay) February 17, 2020
Eric Bailly engaged in 5 aerial duels vs Chelsea and won every single one – a perfect 100% success rate.
— UtdArena. (@utdarena) February 17, 2020
His raw athleticism is a fantastic tool. If he remains fit he will improve us significantly. pic.twitter.com/fB1SOYbXuR
But it didn't take him long to settle back in and he produced reminders of his undoubted quality alongside Maguire and Luke Shaw in a United back three.
He slotted straight back into the team and it didn't appear as if he had gone over six months without seeing first-team action.
The Ivorian produced one incredible block to deny Kovačić when Chelsea were threatening to mount a fightback.
Big performances from the likes of Bailly and Fred tonight - big three points. You can see Bruno's quality already too.
— Scott Saunders (@_scottsaunders) February 17, 2020
Maguire should've been sent off IMO, but it's referee's interpretation.
Nevertheless, three points.
It was not a flawless display but one full of promise and United's fans will be pleased to have Bailly back available once again.
Looking Ahead
The Blues face another stern Premier League test on Saturday as they come up against former boss Jose Mourinho and Tottenham to Stamford Bridge.
United are back in action on Thursday night when they travel to Belgium to take on Club Brugge in the first leg of their last 16 Europa League tie.
Source : 90min