However, the Londoners were expected to make lighter work of their Hungarian opponents, and Sarri has admitted that he had been left unimpressed by the display.
The Italian told BT Sport: "I don't think we played well, we have done a good offensive phase and had a lot of ball opportunities but we conceded too much.
"We have to play every three days, it is very difficult and so we have to have a great mentality. There is a risk to arrive at a match without the mental power and energy. I am very happy with my squad.
"It is a very important in this period of the season to get results, it is not easy but I will have to change a lot players for Southampton and it is not easy to prepare the next match tomorrow - a lot of players will be tired."
Chelsea's win at Stamford Bridge has extended their undefeated streak in all competitions to 10 matches.