Frank Lampard felt proud, honoured and aggrieved after his Derby side were beaten 3-2 at his former club Chelsea.
Chelsea benefited from two Rams own goals, only for the Championship visitors to equalise on each occasion before Cesc Fabregas’ 41st-minute strike proved decisive.
It was in the build up to Fabregas’ first of the season that Derby felt Tom Lawrence was fouled by Davide Zappacosta, only for the Italian to take a quick throw-in and referee Jon Moss to dismiss protests.
Lampard said: “The third goal was a foul. The whole stadium saw that. I turned round thinking we’d got the foul, then looked back and they were in our box.
“VAR should clear up the ones that go slightly wrong. It didn’t tonight.”
Lampard scored a club record 211 goals in 648 appearances and 13 years at Chelsea, but left when his contract expired in June 2014 without having the chance to say goodbye.
This fourth-round clash provided an opportunity to do so and Lampard was serenaded throughout by Chelsea supporters, and he responded by acknowledging them and the Derby fans at the end.
Lampard admitted an afternoon nap – a routine retained from his playing days – had proven difficult on a surreal day.
He added: “I slept well last night. I struggled this afternoon. Sat up all afternoon staring at the ceiling.
“It was exciting for me. (I was) nervous and excited. It is home. Not my current home, but my home for such a long time.
“My overriding feeling is thanks to the Chelsea fans and the Derby fans and pride at the team.”
Lampard refused to dwell on his departure more than four years ago.
He added: “I left quietly. That was the circumstances at the time. I’ve got no bad feelings and I’ve got great relationships.
“It was nice to come back and feel it so positive tonight.”
Chelsea granted Derby special dispensation to field on loan pair Fikayo Tomori and Mason Mount against their parent club.
Tomori scored an own goal after five minutes, but lifelong Chelsea fan Jack Marriott equalised within four minutes.
A near identical own goal – another Zappacosta cross, this time sliced into his own net by Richard Keogh – restored Chelsea’s advantage after 21 minutes.
The lead was short lived as Mount laid on Martyn Waghorn’s leveller after 27 minutes before Fabregas’ winner.
Substitute David Nugent struck the post in the 89th minute as Derby came close to a third equaliser, but Chelsea survived and progressed to a home quarter-final with Bournemouth.
Lampard added: “I’m proud of them. It doesn’t feel like a defeat, but it’s a benchmark for how we want to play from now on in.”