Although Germany international Werner scored in the recent FA Cup win over Morecambe, he went into Saturday's match without a goal in his previous nine league games.
That was already his longest run without a goal since going 11 matches without netting in 2016.
He had a fine chance to finally end that difficult spell in the latter stages when he was put through on goal by Christian Pulisic, but he missed the target when one-on-one with Fulham goalkeeper Alphonse Areola.
Luckily for Chelsea and Lampard, the excellent Mason Mount had already netted what proved to be the winner.
Lampard put on a brave face for Werner at full-time, though he did not completely hide his disappointment.
When asked if he was worried about Werner's dry spell, Lampard told Sky Sports: "I think it's normal".