Barcelona won their most important match of the season against Atlético Madrid on Sunday [4 March] in a game which was considered a virtual cup final in La Liga. The Catalans, who have not lost a single top-flight game with 11 remaining, performed exactly as they have been doing since Ernesto Valverde's arrival.

Far from the exhibitions they have been putting on in recent months, they showed a pragmatic approach in which Lionel Messi, who else, was the key. After a superb set piece – his fifth of the campaign - he gave Barca what they needed against reliable Atlético.

However, the success came at a cost a week before their Champions League last-16 second leg clash with Chelsea. Andrés Iniesta, Barcelona's engine and GPS, suffered an injury and is considered a serious doubt to face Antonio Conte's side next week, according to AS.

Though the club have confirmed that Iniesta will now undergo tests to determine the full extent of the injury, "it appears unlikely he will be available to face Chelsea" next Wednesday [14 March] at the Nou Camp, according to the report.

But the most worrying issue Barcelona face against Chelsea is the knee injury suffered by Gerard Pique, with Valverde having admitted the Spaniard is currently playing through the pain. During the second half against Atletico, he was unable to run, with fans and the media expecting him to be substituted. But he was not.

"It is an injury he can play through," Valverde said, according to AS. "It is not a serious injury, and with two or three weeks on the fringes he'd be fine. He is risking it but he is doing well. It depends on if he gets a blow in that area. We are going to continue like this for the moment."

Leaving Messi aside, Barcelona's spine is formed by Marc André ter Stegen, Piqué, Sergio Busquets, Iniesta and Luis Suárez. After their victory against Atlético, Barcelona are likely to rest some of their most trusted performers when they travel to La Liga's bottom club Malaga this weekend [10 March] but it is unclear whether both Piqué and Iniesta will recover before the game against Chelsea.

Even if Piqué can play - it is clear he is not 100% fit - in such a big game against the Premier League champions with the tie on a knife-edge after the first leg finished 1-1, it could be vital. At this level, the difference between a victory and a defeat can be defined by a single action. The devil is in the detail. Just ask Andreas Christensen.

The lack of planning last summer is the main burden Valverde must carry on his shoulders, because after 27 games unbeaten, having reached the Copa del Rey final and the business end of the Champions League, he has no replacements for some of his key players.

The reality is having received €222m [£195m] for Neymar [The Guardian] they have spent €147m [£135.5m] on Ousmane Dembelé [BBC Sport] – who is yet to recapture his best form during an injury-laden spell - and the Champions League cup-tied Philippe Coutinho for €160m [£145m, Goal.com].

Though their form is magnificent – Barcelona have not lost any of their last 33 official games - there are plenty of sign of fatigue. Chelsea might be underperforming domestically but they showed they can beat them at Stamford Bridge, where Willian hit the post twice before opening the scoring. Only a mistake let Barcelona back into the picture.

However, Valverde can rely on "the genius" Messi, who settled the Atletico 'cup final' by scoring a third free-kick in as many Spanish league games. "Believe me, I have never told him how must he throw the set pieces," the coach admitted. "When I was on the rival bench, I was always afraid when he took the chance to shoot. As a rival, fear is huge. When he is on your side, you have hope. It is a pleasure. It is wonderful."