Casillas suffers one of his strangest errors

The Spanish goalkeeper, who is currently enjoying a very strong season with the Portuguese club, endured a calamitous error only four minutes into Porto's 3-2 victory over Braga. 

It all happened from a counter-attack. Claudemir burst down the left for the hosts, reaching the edge of the area before squaring for Wilson Eduardo, who was free in acres of space.

When this pass happened, however, Casillas raised his arm, asking for an offside that simply didn't exist. The shot from Eduardo was not good, and Casillas, still distracted by the offside call, got a hand to it.

But he could only palm it into his own net, meaning that the goal had to count as an own goal. Even legends make mistakes. 

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