Reports in Italy on Thursday stated that a deal has been struck between the two clubs, with Lucas left to just agree personal terms with the Italian giants.
However, the Brazilian outfit have dismissed the reports, with Paulo de Jesus Lopes claiming that they have held official talks only with Manchester United.
"I'm not aware of this information," he told Lancenet. "I was with (Sao Paulo president) Juvenal Juvenicio (Wednesday and Thursday).
"We sat only to negotiate with Manchester United, but their offer was not good enough."
Lucas, 19, is one of the best young players in world football and is currently in action for Brazil at the Olympics.
He has previously said he will make a decision on his future following the Olympics after Sir Alex Ferguson confirmed United's interest last month.
Is a match jersey is not your style, check out the Manchester United vintage polo. Great for the pub or golf outing.
Check out the Manchester United Full Zip Jacket.
The Manchester United Nike Swoosh t-shirt is too cool. Get in the Gear!
The white Red Devils t-shirt shows your passion for the red side of Manchester.
The Manchester United Supporters Soccer ball from Nike is great for any fan of the Red Devils.
Show your love for the Red Devils with a team poster in your room.
The 2012/13 Manchester United home replica soccer jersey.
Manchester United started out called Newton Heath with the green and gold colors. Go Retro!
The 2012/13 Manchester United away replica soccer jersey.
The Manchester United backpack is perfect to carry your gear to the field or take it to work or school.