Olivier Giroud's overhead kick – awarded by VAR – handed Chelsea a vital 1-0 away win against Atletico Madrid, putting Thomas Tuchel's men in control of the last-16 tie
In a predictably-tight encounter, Giroud acrobatically hooked home with 20 minutes left but celebrations were muted as the linesman's flag was instantly raised
 However, the ball had deflected off Mario Hermoso rather than Mason Mount, which was spotted by VAR, and after three minutes of deliberation the goal was awarded
La Liga leaders Atletico were forced to play their home leg over 3,000 kilometres from Madrid due to Spanish restrictions on arrivals from Britain to control the spread of COVID-19 infections
Thomas Tuchel was facing his toughest test since joining Chelsea but set up his team shrewdly in Bucharest, keeping a lid on Luis Suarez while controlling possession throughout
 Atletico didn't manage a shot on target as Chelsea put themselves in pole position to reach the quarter-finals
 Tuchel will be without Mason Mount and Jorginho in the second leg at Stamford Bridge on March 17 as they will be suspended after being booked
Callum Hudson-Odoi - singled out by his manager in the draw with Southampton - was a surprise starter on the right for Tuchel in a cagey opening to the game
There was a booking inside 60 seconds for Mount for a foul on Joao Felix, meaning he will be suspended for the second leg at Stamford Bridge next month
Then Edouard Mendy almost contrived to pile more misery on the visitors after a heavy touch in the penalty area but Saul was unable to make the most of the goalkeeper's mistake
The Premier League side then started to dominate possession and a long-range effort from Marcos Alonso represented the first shot on target from either side
There were signs that Atleti were set to be more adventurous in the second half as Suarez saw an effort deflected wide and Felix fired an overhead kick off target
Although Chelsea were wasteful in the final third, Tuchel's side controlled the ball in shrewd fashion and all that was missing was a final finish
That changed with 20 minutes remaining
Alonso got forward well and his cross was deflected into the path of Giroud, who produced a superb overhead kick from 12 yards that found the bottom corner
It was immediately ruled out for offside, with Mount deemed to have knocked the ball forward for his team-mate, but after a lengthy VAR review it was adjudged Atletico centre-back Hermoso had got the decisive final touch
A crucial away goal that leaves Chelsea in a fantastic position to reach the last eight
This was another subtle reminder from the French striker that he can be a dangerous option for Chelsea still in big games
 For the majority of the evening, Chelsea struggled to find a final killer pass into their frontmen but that didn't deter Giroud, who was always sniffing out a chance, always looking for a half a yard to take advantage of
 His moment came with 20 minutes remaining and he took it in typical classy fashion, with a little help of course from VAR
 At 34-years-old, he remains at the top of his game
"If you see him on a daily basis you cannot be surprised," Tuchel said
"He is totally fit, his body is in shape, his physicality is on a top level and mentally I have the feeling he enjoys every day
 This is the level he needs to be
"He trains like a 20-year-old, he is a guy who is serious and a mix of joy
"
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>