Champions League semi-finals: Alex Ferguson received a congratulatory text message from Jose Mourinho after Manchester United eliminated Roma to reach the Champions League semi-finals but it is unlikely his phone will be bleeping with the Chelsea manager's number if Milan go the same way in the San Siro tonight.

Thousands of May Day demonstrators were marching in Milan as Ferguson and his players arrived yesterday and the United manager continued the theme of protest by accusing Mourinho of having "no principles".

Relations between the two have drastically deteriorated as the season has entered its closing stages and Ferguson made it clear diplomatic relations have been called off with a man he described on Friday as "having no respect for anyone but himself".

Ferguson chose his words carefully and with a measure of regret because at this stage of the Champions League he is aware by becoming embroiled in a public war of words he is detracting from European football's premier club competition. However, the United manager said he felt compelled to speak out after Mourinho, in his inimitable style, described Cristiano Ronaldo as having "no education" and questioned the newly-crowned PFA Player of the Year's "difficult childhood" in Madeira.

"That is below the belt," Ferguson responded. "In fact, it is very below the belt. Maybe it's a tactic to unsettle the boy but, if so, he is barking up the wrong tree. To bring class into it is totally wrong."

Brought up in the Govan district of Glasgow, Ferguson has taken umbrage to Mourinho's remarks because of his own working-class roots. "Coming from a poor background does not mean you are uneducated and it does not mean you have no principles," he said. "Ronaldo has principles and that is why he has not responded to this."

That apart, Ferguson was in a relaxed mood as he reflected on what promises to be an enthralling night. He was relishing the sense of occasion as he reflected on United's 3-2 first-leg lead and the "massive performance" needed to make an all-Premiership final.

Wayne Rooney's winner at Old Trafford eight days ago means United are marginal favourites and their chances have been enhanced by the return from injury of Nemanja Vidic and Rio Ferdinand. Louis Saha is expected to be on the bench in a 4-3-2-1 formation in which the emphasis, Ferguson said, would be to attack. "We . . . accept Milan are likely to score so the safety net is to get an away goal. I don't think sitting on the edge of the box will do us good."

Acknowledging Kaka, Milan's gifted Brazilian, was the Rossoneri's "obvious threat", Ferguson otherwise radiated confidence. At one point in his press conference he seemed to be taking notes and he left behind a piece of paper containing the words in pencil: "Milan 1 Man Utd 2".

Ferguson is "praying" Paul Scholes, who was suspended from the 1999 final and is one yellow card away from a ban, does not suffer the same fate again. "It would be a tragedy," he said.

• Guardian Service