Chelsea coach Claudio Ranieri wept on the Highbury pitch and was mad with joy after his team beat Arsenal 2-1 on Tuesday to earn a place in the Champions League semi-finals for the first time.
The 52-year-old Italian, whose job has been under threat since Russian billionaire Roman Abramovich bought the west London club last July, said: "To describe my joy is difficult...I was mad...30 seconds of delirium."
Chelsea, drawing 1-1 after the first leg, had not beaten their city rivals in 17 matches, 14 of them under Ranieri.
"This victory can change something," Ranieri said. "We must believe in ourselves. It is history," he added.
Chelsea have never before progressed beyond the Chamopions League quarter-finals.
Ranieri said he was not pleased to be meeting Monaco in the semi-finals after the principality side came from behind to beat Real Madrid on away goals.
"It's not good news because I know Real Madrid very well," said Ranieri, who coached Madrid's rivals Atletico as well as Valencia before moving to Chelsea in 2000.
"If Monaco won it is because Monaco have very good players, a good coach and a good fitness coach," he said.
Monaco coach and former France captain Didier Deschamps is a former Chelsea player and his fitness coach Antonio Pintas worked with Ranieri's Chelsea predecessor Gianluca Vialli.
Ranieri added, however, that after Tuesday's victory anything was possible. "Champions League is a gamble."
Chelsea's Italian coach has suffered constant speculation that he would be sacked at the end of the season in a wholesale clearout since Abramovich's arrival but said the Russian joined him and the the players in mad celebrations after the game.
BIG BLOW
Arsenal coach Arsene Wenger, who last week was looking at a treble of trophies, conceded that the defeat was a big blow after Saturday's 1-0 loss to Manchester United in the FA Cup.
"Once you hit the wall it takes some time to recover," he said, adding that it would be difficult to lift his players for premier league matches at home to Liverpool on Friday and away at Newcastle United on Sunday.
Arsenal lead the table by four points from Chelsea but also have a game in hand.
Wenger said the blow of Tuesday's defeat was all the greater because Monaco are a beatable team and he rated Chelsea's chances of winning the semi-final at 80-20.
"Chelsea are just on the way up, while we're on the way down a little bit. We've crossed on the way," the Frenchman said.
"The whole team looked tired. We now have to survive over the weekend. Football is cruel," he added.