Barcelona maintained their perfect start to the season with a 5-2 victory over Real Betis on Saturday, but the performance exposed two defensive vulnerabilities that Paris Saint-Germain and Real Madrid could look to exploit in the coming days.

Hansi Flick's side have now won all nine of their La Liga matches, scoring 39 goals and establishing a new club record for consecutive victories at the beginning of a league campaign.

Their latest triumph at Estadio de La Cartuja featured another spectacular goal from Lamine Yamal, who also assisted Gabriel Jesus, while Rodri, Eric Garcia and Dani Olmo added their names to the scoresheet.

However, the final score did not entirely reflect the difficulties Barcelona encountered before Betis midfielder Facundo Bernal was sent off following an altercation with Yamal early in the second half.

Manuel Pellegrini's side twice found a way through the visitors' defence, while Giovani Lo Celso also had a superb goal disallowed following a VAR review for an earlier handball by Cucho Hernandez.

Barcelona eventually took advantage of their numerical superiority to complete a convincing victory, but the hosts had already demonstrated two ways of unsettling Flick's team.

Those weaknesses could become particularly significant during an exceptionally demanding week, with Barcelona visiting PSG in the Champions League on Tuesday before hosting Real Madrid in El Clasico on October 25.

How Real Betis exposed two weaknesses in Barcelona's defence

Barcelona's aggressive defensive line has been fundamental to their extraordinary attacking performances under Flick.

By pushing their defenders high up the pitch and applying immediate pressure after losing possession, the Catalan giants restrict opponents' time on the ball and regularly recover possession in dangerous areas.

However, the same approach leaves space behind the back four when the initial pressure is bypassed.

Betis demonstrated that vulnerability shortly after half time.

With Barcelona leading 3-1, Fermin Lopez lost possession in an advanced position, allowing Lo Celso to recognise the space behind the visitors' defence.

The Argentine played a perfectly weighted through-ball into the path of Abde Ezzalzouli, who raced clear and finished past Joan Garcia to reduce the deficit.

The goal illustrated how quickly Barcelona can become exposed when opponents escape their pressing structure and attack before the defenders have recovered their positions.

Betis had already threatened through rapid transitions during the first half, with Hector Bellerin forcing an important save from Garcia shortly before Rodri restored Barcelona's lead.

The visitors' other defensive weakness was evident in the 27th minute, when Valentin Gomez equalised.

Pablo Fornals delivered a cross into the penalty area, where Gomez rose above young defender Xavi Espart to head home.

Unlike Abde's goal, which exposed the space behind Barcelona's high line, Gomez's equaliser highlighted difficulties defending aerial deliveries into the box.

The two situations required different defensive responses, yet both offered evidence that Barcelona can be vulnerable even when dominating possession.

Flick's side enjoyed approximately 69% of the ball and registered 18 attempts against Betis, but their control did not prevent the hosts from creating dangerous opportunities.

The defeat of Betis ultimately underlined Barcelona's attacking superiority, although Bernal's dismissal also changed the balance of the encounter before the visitors extended their advantage.

Why PSG and Real Madrid could present a bigger test for Flick

Barcelona's next two opponents possess the individual quality to punish those defensive weaknesses more ruthlessly.

PSG, who welcome the Spanish champions to the Parc des Princes on Tuesday, have several attackers capable of exploiting space behind a high defensive line.

Ousmane Dembele and Desire Doue offer pace, close control and intelligent movement, while Luis Enrique's midfielders possess the technical ability to progress the ball under pressure.

If PSG can bypass Barcelona's initial press, their forwards could find opportunities to attack the space that Abde exploited so effectively on Saturday.

However, that approach also carries risks.

Barcelona's pressing has been exceptionally effective throughout the campaign, and attempting to play through it can result in dangerous turnovers close to goal.

The tactical contest will therefore depend partly on whether PSG can maintain possession long enough to exploit the space behind Flick's defence.

Real Madrid present a different challenge when the two Spanish giants meet on October 25.

Kylian Mbappe's acceleration and ability to time runs behind defenders could prove particularly dangerous against Barcelona's aggressive defensive positioning.

Jose Mourinho's side have also developed a significant threat from set pieces, scoring seven goals from dead-ball situations in their opening 10 matches.

Three of those goals came from Arda Guler corners during Madrid's remarkable 4-3 Champions League comeback against Roma, illustrating the effectiveness of their rehearsed attacking movements.

Although Betis's first goal on Saturday came from a cross in open play rather than a set piece, Gomez's aerial success will have provided another example of how Barcelona's defenders can be challenged inside their own penalty area.

Madrid's threat from corners and free kicks could therefore provide an additional examination of Flick's defensive organisation.

Nevertheless, Barcelona approach both fixtures with considerable confidence.

Their nine consecutive league victories, combined with an unbeaten record across all competitions, demonstrate that the team's strengths have comfortably outweighed its weaknesses so far.

Yamal remains in outstanding form, while the return of Raphinha against Betis offers Flick another attacking option ahead of the crucial fixtures.

The German manager must now decide whether adjustments to his defensive positioning and aerial organisation are necessary against opponents capable of taking greater advantage of the openings Betis exposed.

Barcelona's latest five-goal display reinforced their status as one of Europe's most formidable attacking teams, but the coming week will test whether their defensive structure can withstand the same pressure at the highest level.