Chelsea face an Atletico Madrid side on Tuesday suffering their worst dip in form all season, still recovering from an injury list worsened by a spate of coronavirus positives, and with coach Diego Simeone close to abandoning the system that has sent them to the top of La Liga because he is running out of the right players to play it.
The weekend defeat by Levante was Atletico's first at home since December 2019. It also made it five points picked up in their last four games. And it was the seventh consecutive match that they had failed to keep a clean sheet in. That has not happened before in the nine years that Simeone has been in charge at Atletico.
The performance at the weekend was far from awful. Levante's goalkeeper Daniel Cardenas was man of the match making a string of saves, Luis Suarez hit the crossbar, Angel Correa scored a goal that was harshly ruled out and Jan Oblak looked to have been fouled in the area when he went forward for a last-minute corner. It was as he was running back that Levante got their second.
But perhaps the worst news from the defeat was an injury to Jose Gimenez and the Uruguayan defender's absence for the game in Bucharest creates a selection dilemma for Simeone.
He struck gold earlier in the season when he started playing 3-5-2. Mario Hermoso, Stefan Savic and Gimenez were water-tight as a back three and only conceded six goals in the first 16 games of the season. The system worked in an attacking sense too with Kieran Trippier effective as a right wing back and Yannick Carrasco doing the same down the left.
The problem with Simeone's desire to play three centre- backs is that he only has four in the squad. One of those (Gimenez) is injury prone, and another (Felipe) has struggled for form this season and does not seem to enjoy the system.
Despite Trippier being banned, Gimenez missing games, and the impressive Hermoso also being ruled out – one of many coronavirus positives – Simeone has stuck to his guns. But on Saturday against Levante he caved in and went back to 4-4-2 when Gimenez got injured in the second half. The change brought about Atletico's best spell of the game but they failed to take their chances and are now just three points clear of second-placed Real Madrid who have played a game more.
The dip in form has also delayed the passing of a personal landmark for Simeone. He will be 10 years in the job this December and needs one more win to go past Luis Aragones as the coach with the most victories in the club's history. Even more impressive, Aragones managed his 307 in 661 games. Simeone has only taken charge of 510.
The 1-0 win has been the most common result from those games and despite recent blips his team have the best defensive record again this season.
But there is a new more expansive dimension to their attacking play too. Simeone has finally responded to criticism that the team play with the handbrake on too often despite having Formula One attacking talent. He will not give up the basics though.
'What is Atletico Madrid?' he asked rhetorically in a recent radio interview. 'We counter-attack, we are strong physically, obviously we have talent but, above all, we are a tough team. The day you go away from that you are not Atletico anymore.'
Chelsea brings back fond memories for Atletico, who got past them en route to the 2014 final. Atletico beat them 3-1 in the second leg semi-final and former Atletico full-back Filipe Luis, who spoke to Sportsmail in the build-up to the game, remembers the match fondly.
'We were dominating possession and Fernando Torres scored for Chelsea,' he said. 'I said: 'Well, let's carry on, let's enjoy this'. Chelsea were obliged to reach the final and we were enjoying the moment, enjoying playing the semi-final.
'We were relaxed, cut loose, enjoying the game and it was incredible. It was drubbing really. And it wasn't luck. It was all studied. Behind Ashley Cole, there was space for a lot of balls. We had studied that. On Cesar Azpilicueta and Gary Cahill's side: we knew that Azpilicueta would come out a long way to make the challenge and leave space behind him and that Cahill didn't cover there.
'David Luiz was studied closely too, although he didn't play in the end. We had studied the counter-attack led by Willian, who was a very dangerous player. And Torres who was quite isolated. It was a brilliant game.'
Atletico Madrid were beaten 4-1 in extra-time in the final and would be beaten finalists against two years later, on both occasions by Real Madrid.
Simeone is determined that despite missing players, being on a bad run, and not being able to play at home his team will go through.
His response to news that the home leg was being moved to Bucharest summed-up the attitude he has instilled in his team: 'We are ready to play the game wherever and whenever,' he said. 'There is no problem.'