Avram Grant's 15-year friendship with Sir Alex Ferguson was at breaking point last night after the Chelsea first-team coach revealed that the Manchester United manager had refused to speak to him after the acrimonious Barclays Premier League defeat at Stamford Bridge last week.

In his opening salvo in the build-up to the Champions League final between the sides on May 21, Ferguson responded by claiming that Grant would “say anything” in an attempt to destabilise his side's defence of the league title.

As the antithesis of his predecessor, José Mourinho, Grant has shied away from such mind games, but clearly feels that United are vulnerable. While the fallout from last week's mass brawl after the match has damaged relations between the clubs, the catalyst for the latest row came when Alan Curbishley claimed that United deserved to be champions and that he would raise a glass to toast Ferguson's tenth Premier League title. The West Ham United manager was last night forced to issue a statement pledging that his side would give their all when they face United at Old Trafford at lunchtime, but the clarification came too late for Grant.

“I've never seen a comment like Curbishley's,” he said. “He was wrong to do that. It's not a good message for your players, but I don't think it's easy for United to play with this pressure.

“Alex was so angry after last week's game I couldn't speak with him. I think I know the reason. He picked a team against Barcelona, and a team against us. He thought he could make a good result here anyway.”

Ferguson reacted with disdain and implied that Chelsea have not always acted properly themselves, a comment thought to refer to previous controversies involving Ashley Cole, Rio Ferdinand and Anders Frisk, the referee.

“They are prepared to say and try anything, Chelsea,” Ferguson said. “So let them get on with it. I have got a team that can answer all the questions. I am getting too old for all the other stuff. I don't know why he is suggesting there is going to be anything untoward. Chelsea should know better than anyone about these situations.”

Grant, who, as an unknown coach of Maccabi Tel Aviv, first met Ferguson when he was invited to study a United training session 15 years ago, has seen this week that psychological warfare can prove counter-productive, with Didier Drogba making Rafael BenÍtez, the Liverpool manager, eat his words, but he is determined to pile pressure on United. Grant is also taking heart from his experiences at Tel Aviv, when he overhauled an eight-point deficit to win the Israeli league in 1995, and the infamous implosion the next year of Kevin Keegan’s Newcastle United, whom Chelsea visit on Monday.

“I understand why United are nervous,” Grant said. “They fought all the time with Arsenal and, when they beat them off, they must have thought everything was OK. Now Chelsea have come up.

“We were behind them for a long time and now we’re level with them. We like the challenge to chase, to chase, to chase. I’ve done it in Israel. We were champions having been eight points behind once. I remember the season when Newcastle lost the lead and hope it happens again. I will buy it. We want United to drop points, of course, but we have to do our job.”

Whether he will keep his job beyond the end of the season is still in doubt, although Grant is not letting the uncertainty disturb him. The Israeli is convinced that he will be retained on the basis of his achievement in taking Chelsea to the final two in both leading competitions, but his conversations with Roman Abramovich have not provided such confirmation. “I spoke with Roman, but it was a private matter,” he said. “I have a feeling that you know that he’s happy, very happy.

“Do I look worried? No. About my personal life, I don’t know what I’m doing tomorrow. Professionally I know what Chelsea need to do tomorrow, a week from now or two years from now.”