Lampard’s side secured a 2-1 win against Lille in the Champions League to seal their first European victory under their club record goal-scorer.
The youthful Chelsea FC side have earned plaudits for their entertaining style of football over the past couple of weeks as they find their stride.
Lampard has been lauded for giving youth a chance to shine in the team, with Tammy Abraham, Mason Mount and Fikayo Tomori all excelling.
Abraham broke the deadlock at Lille before Chelsea FC conceded from a set-piece to leave the score at 1-1 during the half-time break.
However, Willian netted a late winner to secure three points as the Blues made amends for their 1-0 loss to Valencia at Stamford Bridge last month.
Chelsea FC conceded twice from set-pieces in a 2-1 loss to Liverpool FC in their last game in September before a 2-0 victory over Brighton last weekend.
Blues legend Sinclair, who made 218 appearances for the west London side, believes Lampard needs to work on his team’s ability to defend from set pieces despite their small size.
Sinclair wrote on Twitter on Wednesday night: “Achilles heel for Chelsea this season from set pieces, very small side and I don’t like zonal marking at the best of times.”
Chelsea FC will return to Premier League action with a trip to Southampton on Sunday afternoon.
The Blues are in seventh spot in the top flight table and a point adrift of fourth-placed Arsenal.
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