Three-time FIFA World Player of the year Ronaldo is set to become an addition to Milan's struggling forward line.
But the exact timing of the long-sought deal - said to be in the region of six million euros - is still unsure.
As the clubs continued to thrash out conditions, the 30-year-old Brazil legend flew to Milan to salute the Rossoneri fans at Thursday night's Italian Cup semi-final first leg tie against Roma.
But a deal will only be finalised "on Monday or Tuesday" after the results of medical tests are known, Milan attorney and board member Leandro Cantamessa told ANSA.
Milan CEO Adriano Galliani would only say he had sent Real another offer.
"We are negotiating, let's see how it goes," Galliani told Sky Italia.
The Milan exec and No.2 to Italian Premier Silvio Berlusconi also stressed that "everything depends on the results of the medical tests".
The tests are the major uncertainty hanging over the deal - both in timing and outcome.
Some sources indicated Ronaldo - who has had major weight and fitness problems during his four years at Real - could pass muster in time for an on-field presentation before the Roma match.
But Cantamessa, the Milan lawyer and director, indicated that Ronaldo would be put through his paces and undergo lab work over the weekend.
After that, "Monday or Tuesday could be the day the final touches are put to the deal," Cantamessa said.
In Madrid, Real's technical secretary Franco Baldini said Ronaldo would only leave the club if Milan's offer was judged "reasonable".
Spanish sources said Milan would be paying less than the eight-million-euro fee that has been widely aired.
They said the price would probably come down to around six million.
The move has been in the air for weeks now, ever since Real coach Fabio Capello took Ronaldo off the first-team roster.
Galliani has reportedly agreed personal terms for the move in a meeting with Ronaldo's agent.
If sealed, Ronaldo's new contract is expected to run until the summer of 2008, just like his existing deal with the Spanish giants.
AC would effectively take the star and his hefty wage bill off Real's hands.
Ronaldo is reportedly willing to dig into his own pocket to get out of his Real contract.
He is prepared to do this, soccer watchers say, because his existing contract requires him to split his huge sponsorship revenue 50-50 with the Spanish club.
The new contract with Milan will have no such stipulation, sources familiar with the negotiations say.
Even though his best days are behind him, Ronaldo could still provide much-needed finishing skills for Milan, whose attack is suffering a goal drought.
Italy star Pippo Inzaghi and Brazilian striker Ricardo Oliveira - deputising for off-form Italy forward Alberto Gilardino - have failed to find the net in Milan's last few games.
Pundits say even a diminished Ronaldo would boost Milan's striking force.
Ronaldo wants to keep playing for a big club in a top championship, unlike his team-mate David Beckham and former Real colleague Luis Figo, who have been lured to less prestigious leagues by massive offers from American and Saudi clubs respectively.
And Real have found it hard to offload a player with such a high salary anywhere else.
Although past his prime, Italian soccer pundits say Ronaldo would strengthen a Milan attack weakened by the departure of Andriy Shevchenko last summer.
If a deal is sealed, it will be a field day for the Italian media, which has long been waiting to hail the return of a prodigal son.
Ronaldo plied his trade with Milan's cross-town rivals Inter for five seasons between 1997 and 2002.
His term at Inter was dogged by injuries and latterly a running feud with coach Héctor Cúper, but he still scored a string of memorable goals.
It was while he was an Inter player, in 1998, that Ronaldo suffered a still-mysterious fit ahead of Brazil's 3-0 defeat to France in the World Cup Final.
He was still on Inter's books when, after two operations and 20 months of rehabilitation, he came back for the 2002 FIFA World Cup, in which he scored two goals against Germany in securing Brazil's fifth World Cup title.
Ronaldo scored against every team he came up against except England in the quarter finals and was the top scorer of the tournament with eight goals.
Later in 2002 he won the World Player of the Year award for the third time and transferred to Real Madrid for approximately 40 million euros.
