Chelsea's defensive issues are so bad that they need to score several goals each game to stand a chance of winning, says captain Cesar Azpilicueta.
They have conceded nine times in five Premier League games this season and were 2-0 and 3-2 up against Southampton on Saturday before drawing 3-3.
Last month Chelsea came from 3-0 down to draw against West Brom.
"When you're weak defensively sometimes we feel like we have to score three or four each game," Azpilicueta said.
"I see football as a collective. When we don't score, as a defender I think how can we put our attacking players in better situations.
"Through a season you are not going to be winning 3-0 or 4-0 every week. You have to work to get results and at the moment we have to improve that."
Chelsea play their first Champions League Group E match against Europa League champions Sevilla at Stamford Bridge on Tuesday.
Having spent £220m during the recent transfer window, the Blues are seventh in the Premier League and have won only two of their opening five games.
Manager Frank Lampard said: "I'm aware of the stats and the other stat is we've conceded second fewest shots.
"It helps to narrow down the issue. It's something we're aware of with recruitment and on the pitch with the players to make sure we set up well. We want to concede less, as do all teams at the moment."
Chelsea have no new injury concerns for the Sevilla match. Goalkeeper Edouard Mendy is a doubt after missing the game against Southampton with a thigh injury sustained on Senegal duty.
Left-back Marcos Alonso remains suspended following his red card against Bayern Munich last season.
Sevilla coach Julen Lopetegui will again be without forward Oussama Idrissi and centre-back Jules Kounde.
MATCH FACTS
Head-to-head
This will be the first European encounter between Chelsea and Sevilla.
Chelsea
Chelsea have won one of their past nine Champions League matches against Spanish opponents (D5 L3) - a 2-1 win at Atletico Madrid in September 2017.
Chelsea have lost their past two Champions League matches - they have never lost three consecutively in major Uefa European competition.
Chelsea have lost their first match in a Champions League campaign twice in 16 previous seasons in the competition (W10 D4).
Chelsea manager Frank Lampard will become only the second Englishman to manage in two Champions League campaigns, after Sir Bobby Robson (three - 1993-94, 1998-99 and 2002-03). The last Englishman to manage an English side in consecutive European Cup campaigns was Joe Fagan in 1983-84 and 1984-85 with Liverpool.
Sevilla
Sevilla have won each of their past three major European matches against English teams, beating Manchester United in March 2018 in the Champions League last 16, Wolves in August 2020 in the Europa League quarter-final and United in August 2020 in the Europa League semi-final.
Sevilla have won only one of their seven away major European matches in England (D3 L3), a 2-1 win at Old Trafford in March 2018. All seven of their away games have been against different teams - Bolton, Tottenham, Arsenal, Man City, Leicester, Liverpool and Man Utd.
This is Sevilla's sixth appearance in the Champions League - they have not lost on matchday one since they were beaten 3-0 by Arsenal at Emirates Stadium in 2007-08.
Stats suggest Chelsea looking good for knockout stages
Sports data analysts Gracenote says Chelsea have 83% chance of progressing to the knockout stages of the Champions League.
Simon Gleave, head of sports analysis at Nielsen's Gracenote, says: "The chance of Chelsea reaching the knockout stage was improved by the draw from 74% to 83% according to the Euro Club Index (www.euroclubindex.com
).
"This was due to a combination of avoiding higher ranked teams than Sevilla from the top seeds and the better pot 3 and 4 teams being drawn in other groups."