Alex Ferguson decided the time was ripe last night to step up his calculated campaign to undermine Chelsea's title ambitions.

He said the Premiership leaders had "no form" and, undoubtedly enjoying their sudden vulnerability, he suggested Liverpool could deliver another demoralising setback for Jose Mourinho in tomorrow's League Cup final.

Never slow to pick up on a rival manager being under pressure, Ferguson also questioned Mourinho's reasons for complaining to UEFA about the content of an alleged meeting between Barcelona's coach Frank Rijkaard and the referee Anders Frisk at half-time in Wednesday's Champions League tie. The Manchester United manager chose his words carefully and, having previously been loth to talk about Chelsea's Portuguese coach at great length, he willingly volunteered a withering assessment of Mourinho's possible motives.

"There's obviously some method in it, but what, I don't know," he said. "When we played Milan on Wednesday my assistant Carlos Queiroz was stood in the centre circle speaking to the referee for five minutes. But so was one of their players, Rui Costa. I could accuse Rui Costa - or they could accuse Carlos - but we won't be doing that. You have to trust the referees."

Ferguson, that notorious mischief-maker, has perfected the art of offering journalists a juicy distraction whenever United have lost a crucial match, and rather than dwell on the Milan game he quickly turned his sights on Chelsea. "Anything I say nowadays is treated as psychological warfare or mind games but if you look at the facts, and even Chelsea might have to agree with this - well, they might do - they are not playing as well as they were four or five weeks ago. Plus they've started to lose important players through injury.

"They have three London derbies, including Arsenal, to play, as well as Newcastle, Bolton and ourselves away. And right now they're grasping for form. If they were to lose a league game before playing ourselves or Arsenal they have no form to fall back on."

United are currently nine points behind Chelsea, with an inferior goal difference, but Portsmouth's visit to Old Trafford today and the lunchtime kick-off at Crystal Palace next Saturday offer the chance to close it to three before Chelsea play later that day at Norwich.

"We can't allow this opportunity to go," said Ferguson, speculating about the possibility of a Chelsea collapse. "It's certainly more possible now than a few weeks ago, having seen what I've seen in the last few couple of games. They're looking over their shoulders now. Arsenal and ourselves have the history and experience of winning championships on our side. You get that by winning titles and Chelsea haven't done that.

"Our form is good enough. Chelsea have resilience about them and you know they will defend for their lives if they have to. But that's not necessarily going to win them the league. It might save them the odd draw but winning games is important now. Drawing is not much better than losing."

Approaching the stage of the season that Ferguson refers to as "squeaky-bum time", he cited the fact that United have all four of their strikers available for the first time since October. The fit-again Ruud van Nistelrooy will start his first match since November 27th today and Alan Smith is expected to return after missing the past six weeks.

Warming to his theme, he also speculated that Liverpool, buoyed by their midweek defeat of Bayer Leverkusen, might spring a surprise result at Cardiff tomorrow. "They are taking a lot of history into the final. They've won it more times than anyone - no fewer than seven occasions, including twice against us."

The United manager warned against the temptation to write off his players in the San Siro on March 8th and even breaking into a spontaneous rendition of Hear My Song by Josef Locke. "It was a kick in the teeth to concede a goal so late; horrible when you consider they had not had a shot on target until then. But I don't think the performance was a bad one. I'd like to have taken our chances and if we had gone ahead I'm certain we would have won. But I'm sure we can take them over there." Guardian Service