Chelsea will attempt to kick their Champions League campaign into gear at the second attempt on Tuesday when they visit Steaua Bucharest for their second Group E fixture.
The London club were stunned 2-1 by FC Basel in their first group outing and can ill afford further setbacks with a double-header against Schalke to come.
Chelsea last season became the first defending champions to be eliminated in the group phase and manager Jose Mourinho has described Tuesday's match as "the game that we cannot lose".
"Even a draw, probably, is not a good result for us, so now we have to prepare ourselves," said the Portuguese, who is bidding to win the competition with a third different club.
"We have to get 12 points to be out of any danger, so if we lose there we still have four matches to play and we will have to win them all. We don't want to put ourselves under so much pressure."
Chelsea do not have fond memories of their last visit to Bucharest, however, having lost 1-0 to Steaua in the away leg of a Europa League last 16 tie in March before winning the second leg 3-1.
Centre-back Vlad Chiriches claimed Steaua's goal at Stamford Bridge, but he has since left the Romanian capital for Tottenham Hotspur and was on the bench for his new side's 1-1 draw at home to Chelsea on Saturday.
Juan Mata tipped the momentum of the game in Chelsea's favour after coming on as a half-time substitute at White Hart Lane and Mourinho subsequently confirmed that he would start at Steaua's Arena Nationala.
Should Mourinho elect to make further alterations to his starting XI, Gary Cahill, Samuel Eto'o and Willian are among the players who could be drafted into the team.
Brazilian midfielder Ramires is also available for selection after serving a one-match ban following his dismissal in the UEFA Super Cup defeat by Bayern Munich.
Beaten 3-0 at Schalke in their Group E opener, Romanian champions Steaua warmed up for Tuesday's game with a 3-0 win at home to Poli Timisoara in the domestic championship on Saturday.
Laurentiu Reghecampf's side won a league and cup double last season, but Steaua have not appeared in the Champions League group stage since 2008 and have not won a game in the competition since September 2006.
However, the 1986 European champions boast an admirable home record against English clubs, having lost only one of eight previous encounters.