Chelsea clawed their way into the quarter-final of the Champions League following a sternly-fought 2-1 victory in Lille on Wednesday night.
Despite taking a two-goal cushion into the second-leg, the evening was anything but comfortable for the Blues who found themselves under the cosh from the get-go. Burak Yilmaz halved Lille's deficit from the penalty spot, but Christian Pulisic hit back for the visitors on the stroke of half-time and Cesar Azpilicueta grabbed a second after the restart.
Thomas Tuchel, who has been something of a shining light in an otherwise dark and gloomy period for the club, eventually managed to navigate the ship through the storm, but it was anything but easy. With that in mind, here are three things the German boss got right and one he got wrong on the night.
Wrong - Starting with three in midfield
Chelsea's midfield three didn't really work
The last time Tuchel started a match with three in midfield, Chelsea were being played off the park by Manchester City in December, and while the German has developed a reputation for being tactically flexible, his decision to do the same again tonight caught a few people off guard.
Despite being able to dominate the ball in midfield, the system wasn't really working as it allowed Lille's full-backs far too much time and space in possession. As a result, the Blues were getting overrun on the flanks for much of the first-half, and found themselves 1-0 down after 38 minutes.
Right - Pulisic up front
As mentioned before, Tuchel raised a few eyebrows after starting with two up top, and raised a few more by picking Pulisic as Kai Havertz's partner up top, leaving natural natural strikers Romelu Lukaku and Timo Werner on the bench.
But his decision paid dividends after the American got himself on the scoresheet, and at what was a vital time for Chelsea having gone behind a few moments before. Pulisic never looked truly comfortable up front, which is hardly surprising given his proficiency out wide, but he managed to make his mark when Tuchel and Chelsea needed him to.
Right - Half-time system change
Tuchel recognised the threat of Lille's full-backs and wisely decided to change the system at half-time, bringing Mason Mount on for Mateo Kovacic and reverting back to his usual 3-4-3 system in the process. This nullified what had been Lille's biggest threat all evening as Chelsea now had wide players who were able to track back to stop themselves being overrun on the flanks.
It was also Mount who set up Cesar Azpilicueta for Chelsea's second goal on the night, which effectively put the tie to bed, curling a gorgeous cross in from the left wing which the Spaniard duly - and rather fortunately - dispatched.
Right - Leaving Lukaku out
Given the two-goal cushion Chelsea took into the tie, Tuchel was probably very tempted to start his misfiring £98 million Belgian striker, you know, to try and jolt him back to life. But it's a good thing he didn't. Lille's pressing was immense from the start and Chelsea's forwards had next to no time on the ball all evening.
In essence, their forwards needed to be mobile and to drop into midfield when needed, something Lukaku has shown little desire to do in recent weeks. The 28-year-old was brought on as a substitute in the second-half with the tie effectively over, but once again had little impact on proceedings. A good call by Tuchel in the end.