Caretaker manager Roberto Di Matteo believes defeat for Chelsea against Tottenham Hotspur on Saturday could make Champions League qualification a tall order but is reassured by the club's domination of the fixture for over 20 years.
Chelsea have not lost at home to Tottenham in the Premier League era, the last reverse coming in 1990, but victory has never been more important as they try and close a five-point gap on their London rivals who occupy fourth place.
Defeat, Di Matteo said, would make it difficult for Chelsea to finish in the top four although there is room for optimism with skipper John Terry set to return after missing the midweek defeat against title-chasing Manchester City.
Not such good news is the likely absence of full back Branislav Ivanovic who is doubtful with a thigh injury.
"We're used to these big games, tomorrow is another one, the team is fighting for fourth and for the Champions League next season and we understand that," Di Matteo, who suffered his first defeat since taking over from sacked Andre Villas-Boas on Wednesday, told a news conference on Friday.
"It's a game we play at home and we want to take advantage of our home form and our supporters as well, a win would give us a big lift, if we get a draw we're still in it, but if we lose it will be very difficult.
"We will try, our home form is very good, we haven't lost a game yet in 2012, we would like that to continue."
Chelsea, Tottenham and a resurgent Arsenal are battling for third and fourth places in the Premier League, with Chelsea having the slightly tougher run in.
"I'm certain that we have the toughest run of fixtures from now until the end of the season compared to the other teams, but we're a good team, we have a good squad, an almost fully fit squad as well so we have all the resources we need to be able to challenge," said Di Matteo, who also faces a Champions League quarter-final at Benfica on Tuesday.
Chelsea are also in the FA Cup semi-finals, meaning the games will come thick and fast for Di Matteo's squad.
"We cannot look further ahead than the next game, we haven't got the time to do that because the position we're in doesn't allow us to do that," he said.
"We're playing every three days so we need to utilise the whole squad, select a team that is fresh and can reach the intensity levels you need."
Despite the defeat at City, which with Tottenham's last-gasp draw at home to Stoke City meant the gap between the sides widened to five points, Di Matteo said he took a lot of heart from the performance.
"We were disappointed on Wednesday, but I think it was a great effort from our team and we created the most problems for Manchester City at their ground," he said.
"They are very good at home, so now we go into tomorrow's game with a lot of confidence and belief."