The 20-year-old attacking midfielder, snapped up by PSG in August for a reported fee of 45 million euros with the agreement that he would move in January, is one of the most exciting young Brazilian prospects.
"I am happy with everything that has happened in my life, to have achieved my dream of leaving here with a title. I leave with a heavy heart but happy," he was quoted as saying by L'Equipe's website on Friday having helped Sao Paulo win the Copa Sudamerica on Dec. 12.
"It's time for me to go to PSG. I want to enjoy my last days in Brazil and on Sunday, I leave for France to start my career in Europe. As the club is preparing for the resumption after the mid-season break in Qatar, I will spend the New Year there.
"It is not going to be easy."
Lucas is unlikely to be the last January recruit for Qatari-backed PSG, who top Ligue 1 on goal difference from Olympique Lyon at the halfway point of the 38-game season.
Another Brazilian who will be looking to make his mark in French football when action resumes next week is Lille striker Tulio De Melo after he denied reports of an exit following a difficult first half of the campaign.
"I don't know what you are talking about, no one has told me," he said when asked about the rumours.
"I am under contract until 2014 and I want to help Lille, that's my primary objective."
The north east club, champions two seasons ago, are eighth in the standings, nine points behind PSG.