Liverpool - Chelsea are on the brink of their first Premier League title in four years after Steven Gerrard's mistake helped the leaders secure a vital 2-0 win at Liverpool on Sunday.
Carlo Ancelotti's side are now four points clear of second-placed Manchester United and, even if the champions keep the title race alive with a win at Sunderland later on Sunday, the Blues will be crowned kings of English football if they beat Wigan at home next weekend.
Gerrard had used his programme notes to insist that the hosts would not throw in the towel against Chelsea, even though a Liverpool victory would have aided the title aspirations of bitter rivals United.
Yet the England midfielder's horrendous back pass allowed Didier Drogba to score his 26th Premier League goal of the campaign before Frank Lampard wrapped up a comfortable victory after more lacklustre defending from Rafa Benitez's team.
This game had long since been earmarked as a must-win for Chelsea and a match that would test both their title-winning mentality and mettle. They delivered on both counts.
Rumours of a conspiracy had been sweeping Merseyside in the days before that Liverpool would not mind losing to Chelsea as it would help prevent United from winning a record 19th title.
A banner draped over the Centenary Stand at Anfield before the game "Cockneys For A Day" did little to dispel that theory.
But those suggestions should have been laid to rest inside the opening three minutes, Javier Mascherano's shot from 25-yards deflecting narrowly wide for a corner as Liverpool made the brighter start.
Chelsea were strangely lethargic considering the prize that was at stake.
Despite early attempts by Salomon Kalou and Nicolas Anelka, it was Liverpool who came closest to breaking the deadlock in the opening exchanges as Alberto Aquilani went close to delivering a crushing blow to Ancelotti with a cracking 25-yard effort that clipped the top of the bar.
Aquilani then crumpled under a challenge from Branislav Ivanovic in the area but the referee adjudged there was no foul before Gerrard's clanger 12 minutes before half time brought Chelsea within touching distance of the title.
Gerrard, under no pressure whatsoever, attempted a needless back pass that provided Drogba with an open invitation to pounce, round Jose Reina and slot home in front of the Kop.
That brought the Ivory Coast striker level with Wayne Rooney at the top of the Premier League scoring charts - more importantly it left Chelsea on the verge of their third title in six seasons.
Suddenly, Chelsea were going for the kill. It required a superb challenge by Liverpool's Greek defender Sotirios Kyrgiakos to prevented Nicolas Anelka from making it 2-0, while the visitors felt they should have been awarded a penalty in the dying moments of the first half after claiming that Lucas had clipped Kalou.
Liverpool had started the day with an outside chance of securing a place in the Champions League qualifying rounds, but Benitez's side struggled to recover from falling behind.
Kalou and Florent Malouda, who were both magnificent, were causing all sorts of problems and both had chances to extend Chelsea's lead before Lampard sealed a priceless victory in the 54th minute.
At least Chelsea were not handed the goal on a plate this time, although the defending that led to England midfielder Lampard sliding home to meet Anelka's low cross was poor to say the least.
Liverpool never threatened to mount a fightback and although Chelsea's celebrations on the pitch at the final whistle were subdued, the title is almost theirs.