Maurizio Sarri has admitted that Chelsea endured a "horrible" 15-minute spell in their 3-2 win over Arsenal on Saturday.
The Blues surged into a two-goal lead against their London rivals at Stamford Bridge, courtesy of efforts from Pedro and Alvaro Morata.
However, they went in level with the Gunners at the break after Henrikh Mkhitaryan and Alex Iwobi both struck within five first-half minutes.
Both sides had chances to earn the Premier League points before substitute Eden Hazard crossed for Marcos Alonso to net the winner nine minutes from time.
When asked by BBC Sport how important the win was, Sarri replied: "Very important. In this period for us it's not easy to gain points. Three points is an important target for us, we did very well for 75 minutes but inside that, 15 minutes were horrible.
"It was very, very difficult because we lost the distances between the players and we were unable to cover the lost balls and press like a team, so we were really in trouble. But I think the players were really very good because at 2-2 it was not easy with Arsenal. In the second half we did very well also mentally."
Chelsea have won six of their past seven home league games against Arsenal, the exception being a 0-0 draw last season.
