Karim Benzema’s brilliant equaliser for Real Madrid on Tuesday night was more than a random act of genius. It was a punishment that Chelsea brought on themselves by failing to land the killer blow when they were on top during the first leg of their Champions League semi-final at Valdebebas, demonstrating they cannot simply rely on Thomas Tuchel’s keen tactical mind against Europe’s best.

The lesson was not lost on Tuchel, who knew Chelsea had only themselves to blame after missing a chance to put away the 13-time champions. There was no point complaining about Madrid’s goal coming against the run of play. Zinedine Zidane’s side always had a chance with a striker of Benzema’s calibre and although Chelsea left Spain with a slender edge thanks to Christian Pulisic’s splendid opener, Tuchel will be concerned about his attack’s lack of composure before the second leg at Stamford Bridge next Wednesday.

Tuchel reads the game too acutely not to have spotted the warning signs. The German will know the logical outcome is Chelsea, who need only draw 0-0 to progress, reaching the final at Madrid’s expense. He will be confident in his ability to set up another smart tactical plan. He will back N’Golo Kanté to dominate midfield again, his defence to shine, Mason Mount to be fearless on the ball and Pulisic’s dribbling to unsettle Madrid.

Yet Tuchel will also fear it will not be enough against opponents as ruthless as Madrid. The danger is Chelsea’s supremacy will not be reflected in the final score if their shoddy finishing leaves open the possibility of a Benzema goal. If Zidane ditches his uneven 3-5-2 system for a 4-3-3, Sergio Ramos returns to fitness and Eden Hazard comes alive on his return to west London, it could easily be a different game.

The good news for Chelsea is they are capable of earning the clean sheet that will take them to Istanbul. They have had 16 shutouts since Tuchel’s arrival in January and their structure is so good that they often go through games without conceding chances, let alone goals.

Yet it is not an easy balancing act. The other side of those defensive statistics is that Chelsea have had four goalless draws under Tuchel. They have dropped points in the Premier League because of their blunt attack and have scored more than once in only nine games. Without a potent finisher leading the line, Chelsea remain vulnerable. It will take one lapse of concentration for Madrid to seize control.

Timo Werner fluffed an early chance against Real Madrid, to add to his recent run of erratic finishing.
Timo Werner fluffed an early chance against Real Madrid, to add to his recent run of erratic finishing. Photograph: Quality Sport Images/Getty Images

It means Tuchel needs more poise from his forwards. Although Pulisic did his job in the Spanish capital, taking his goal with aplomb, it was another difficult outing for Timo Werner, who finished far too hesitantly with only Thibaut Courtois to beat in the fourth minute.

Werner remains a conundrum. The £47.5m striker has not had a bad first year in England. The German is a menace when he runs behind defences. He spreads chaos, creates space for teammates and made crucial goals for Hakim Ziyech against Atlético Madrid in the Champions League and Manchester City in the FA Cup, demonstrating his worth to the side.

It is too straightforward to argue Tuchel should discard Werner and turn to a pure striker such as Tammy Abraham, who is increasingly likely to leave this summer. Chelsea have looked dangerous and unpredictable without a conventional No 9, whether it has been Werner, Pulisic, Mount or Kai Havertz through the middle. There are no guarantees that the blend would be right with Abraham or Olivier Giroud up front.

All the same it is impossible to ignore Werner’s goalscoring record. Although the 25-year-old got the winner against West Ham last Saturday, he also contributed a glaring miss against David Moyes’s side and has three goals in his past 33 appearances. For all that Werner can complain about Kanté and Pulisic missing chances to send him through on goal against Madrid, his erratic finishing is a much bigger issue.

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It leaves Tuchel unable to relax. Although one goal has often been enough, it is putting a lot of pressure on the defence to hold firm. It felt unnecessarily dicey when Chelsea played Tottenham off the park in February, took an early lead and almost conceded a late equaliser to Carlos Vinícius, and when they found themselves under late pressure in their FA Cup semi-final against City.

Even West Ham almost hit back after Werner’s miss, Jesse Lingard whistling a volley inches wide. For Tuchel, it is a reminder it only takes a split second for a game to change. He will know Chelsea have the edge over Madrid. But if Werner fluffs his lines again, Benzema will be lying in wait at the other end, ready to pounce and blow Tuchel’s plan apart.