Lazio led Inter Milan 2-0 and 3-2 but ended up losing 4-3 to the champions - for whom Hernan Crespo scored a hat-trick - while AC Milan, who on May 23 play Liverpool in this year's Champions League final, were held to a 1-1 draw by Catania.

Defeats for Empoli and Palermo meant AC Milan and Lazio are certain to finish in the top four, and they will now participate in the two-legged qualifier for Europe's premier club competition.

AC Milan's achievement with two games of the season left is all the more impressive given the fact they were deducted eight points for their part in 'Calciopoli', the Italian match-fixing scandal.

Lazio were also involved in the scandal and were docked three points.

The winners of the third qualifying round will enter the Champions League proper.

AC Milan coach Carlo Ancelotti urged his players to ensure their season would go down in history by beating Liverpool in Athens in 10 days' time.

"We've reached two important targets: at worst fourth place, and the final of the Champions League. But this season could turn out to be unforgettable - it's up to us," he said.

Lazio coach Delio Rossi said he never dreamed his side could qualify for the Champions League.

"We've achieved something that was unthinkable at the start of the season," he said.

"I would have been content with qualifying for the UEFA Cup."

Beaten 6-2 by Roma in the first leg of the Italian Cup final on Thursday, Inter once again showed their defensive frailties as Lazio went two goals up inside the first four minutes at the San Siro.

But Inter reacted positively with Crespo converting crosses from Maicon and Patrick Vieira to bring his side level.

Christian Ledesma's free-kick gave Lazio a half-time lead, only for Crespo to complete his treble with a close range finish in the 80th minute.

Lazio defender Sebastiano Siviglia complained that Crespo was offside, and after taking his protest too far, was sent off.

Inter snatched the winner a minute from time when Italian World Cup winner Marco Materazzi headed in a corner.

Dutch midfielder Clarence Seedorf put Milan ahead in the sixth minute against Catania, before Gionatha Spinesi equalised with an angled volley.

AC Milan coach Carlo Ancelotti resisted the temptation to field a second string side and instead fielded a team that will probably be close to his line-up in Athens, with captain Paolo Maldini, Kaka and Gennaro Gattuso all starting the match.

Down at the bottom, Siena pulled themselves out of the drop zone with a 2-0 home win over Empoli, while Reggina drew 1-1 with relegation rivals Chievo, a result that did neither team a favour.

Parma boosted their survival hopes with a 4-1 home win over already relegated Messina, but Cagliari remain in danger after a 1-0 loss at Fiorentina.

Roberto Muzzi eased Torino's relegation fears by scoring the only goal in a 1-0 win at Roma, one of the 35-year-old striker's former clubs.

Roma have already clinched second place and automatic entry into next season's Champions League.