Thomas Tuchel admitted that Chelsea were “lucky” to keep a clean sheet against Sheffield United in the second half.
Chelsea took the lead in the 24th minute. The move was started by a Mason Mount corner that eventually found its way to Ben Chilwell. The defender fired a low cross into the area and Oliver Norwood knocked the ball into the net.
The hosts did not create an awful lot of chances and they were put under pressure in the second half. Sheffield United gave it a real go but they were unable to forge an equaliser.
Paul Heckingbottam’s side were punished for this in stoppage time as Chelsea netted their second. Hakim Ziyech intercepted Phil Jagielka before he advanced into the area. Chilwell found the forward in the area who netted past Aaron Ramsdale.
The Blues are now unbeaten in 14 games in all competitions under Tuchel. They will face either Man City, Southampton, Man United or Leicester in the FA Cup semi-finals.
Tuchel told BBC Sport that Chelsea made “many little faults” against the Blades:
“Sounds excellent to say we’re through to the semi-finals – it was a tough match. We had a good first half where we controlled everything.
“We lost control in the second half, we were clearly tired. After 14 consecutive matches, I could feel we were tired and we made many little faults.
“We were lucky to keep the clean sheet in the second half but I think it’s the first time in the 14 games we have looked tired. It’s important to go through in the cup and that was the target and we reached it.
“We let them come back because we had full control in first half and second half a big chance with Christian Pulisic to finish the game early. We made too many easy mistakes and lost duels and lost some momentum.
“I could tell in training we were tired and there was a lack of concentration. That can happen sometimes it gets harder to keep the level up – I’m happy we could help from the bench and in the end we have the win so we take that.”