Barcelona's attacking masterclass alone will not win them the Champions League - they need Carles Puyol back

Barcelona all but secured a mouth-watering meeting with perennial rivals Real Madrid in the semi-final of the Champions League thanks to a comprehensive 5-1 win over Shakhtar Donetsk on Wednesday evening, but despite their dominance, defensive frailties remain apparent, and the presence of captain and leader Carles Puyol is required in order to reorganise their fragile back four.

Puyol hasn't featured since January 22 as he combats a knee problem that has escalated from a minor niggle into a season-threatening concern. The 32-year-old has appeared on the cusp of a comeback on several occasions, only for his period of inactivity to be further extended. In the 15 matches he has missed - 10 in La Liga, three in Europe, and two in the Copa del Rey - his team have forged on in their relentless treble hunt, and it would appear that the impact of his absence has been minimal.

However, teams are creating chances against Barca, more so than when Puyol is orchestrating the back four, but are failing to convert them at key moments in matches. Victor Valdes can accept a degree of credit, but poor finishing has also played its part - gaps are appearing that aren't being fully exploiting by the opposition, and Puyol's absence can be seen a major contributory factor to Barca's normally stingy defence becoming more accommodating to attackers.

Puyol may lack an element of refinement in a team positively bristling with ability on the ball, but his uncompromising approach comes with in-built organisational skills that when at full capacity make Barca a well-oiled unit across the back, but when removed from the equation are conspicuous in their absence.