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Chelsea conceded from a set-piece yet again this season in the 2-1 victory over Lille on Wednesday.
The Blues have also let in goals from free-kicks and corner-kicks against Leicester, Valencia and Liverpool.
According to former Chelsea defender Frank Sinclair, Chelsea’s main weakness this season is defending set-pieces.
Chelsea boss Frank Lampard has opted to use the zonal marking system when defending set-pieces and Sinclair insists he isn’t a fan of zonal marking.
Taking to Twitter, Sinclair said: “Achilles heel for Chelsea this season from set pieces, very small side and I don’t like zonal marking at the best of times.”