Chelsea had made wholesale changes, with only Lampard remaining from the team that played Liverpool last time out.
It could have made the home side a bit disjointed, but their task of finding some rhythm was helped by Huddersfield's inability to settle early on.
The League One side were understandably hesitant in the early stages, as a physically imposing Chelsea side - which included fit-again captain John Terry for the first time since 16 December - began to dictate the play.
Chelsea turned up the pressure and Sinclair had an effort cleared off the line by Robbie Williams.
And then Sinclair played a pass inside for Lampard to stroke home a precise low shot into the bottom left corner from the edge of the box for his 100th Chelsea goal.
A predictable pattern ensued as Huddersfield struggled to resist Chelsea's attacks.
But then, as if they sensed they really had nothing to lose, Huddersfield began to come out of their shell.
And it took Terry to prevent an equaliser when he hacked Clarke's header off the line.
However, there was nothing Chelsea could do to prevent the equaliser on 45 minutes when Collins superbly brought down James Berrett's pass and slipped a low shot beyond Carlo Cudicini.
After the break, Chelsea quickly raised the tempo but Huddersfield kept their shape and discipline and were able to hold their own for a while.
But eventually Chelsea's power told as Matthew Glennon failed to hold Lampard's shot and the midfielder reacted fastest to tap in the rebound.
It seemed to knock the stuffing out of Huddersfield, and the offside flag prevented them conceding more goals as two Chelsea efforts were ruled out.
Inevitably, Chelsea did score again and it was a fine Lampard pass that created the opportunity and a smart touch and confident finish from Kalou that rounded off the move.
Chelsea boss Avram Grant: "We are in all the competitions. We won today and we are in the last eight of the FA Cup.
"We missed so many players but we stayed in all competitions.
"I didn't plan for John Terry to play 90 minutes, only 70. But he was looking so good I left him on the pitch. I am very happy to see him back."
Huddersfield boss Andy Ritchie: "It was always going to be a massive task but the lads have not disgraced themselves. We had some good play in the second half.
"They move the ball so quickly and we knew it would be hard for our lads to maintain the effort. But we did.
"We were a little bit in awe of them and I think some of our tackles could
have been a bit stronger physically."
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Interview: Huddersfield manager Andy Ritchie
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