Chelsea manager Thomas Tuchel admits his team was a little fortunate to defeat Sheffield United.

The Blues were in control for much of the FA Cup quarter final against the bottom of the league Blades.

Sheffield United, however, put up a good fight for spells, and could have equalized through David McGoldrick and Rhian Brewster.

Chelsea now take on Manchester City in the semi finals, with Leicester City facing Southampton for a place at the Wembley showpiece.

"On the 14th match in a row, I could feel us after the Atletico game a bit tired, there was a big relief in the team, and that is absolutely normal," said Tuchel to reporters.

"It was also a huge effort mentally against Atletico.

"Then you have a lot of changes, made from me of course, and you have players leaving right now for international duties, so there is a lot to organise, and many unclear situations.

"It was a moment where we arrived yesterday where I didn't feel 100 per cent comfortable or sure that we could continue on the same level.

"I said to the team before, don't over-expect from ourselves in the situation. Put in a serious performance, take the little details, but don't over-expect.

"The first half was okay, the second half when there was the chance for Christian Pulisic that we didn't take, then we lost control, concentration, a bit of momentum and there were many minutes we had to suffer.

"They had two big chances and we were lucky to escape with a clean sheet. But there are a lot of circumstances to explain it, and it's OK.

"After 14 matches the target was to go to the quarter-finals [of the Champions League] and to Wembley, and the team have achieved both of the targets so big compliments to them and well done."