Rudi Garcia has been installed as Roma coach while a trio of candidates will find out in the next 48 hours which of them will succeed him at Lille.
L'Equipe claimed on Wednesday that Garcia, 49, was poised to finalise his move to the Italian capital and he has now signed a two-year contract with the option of a further year after meeting Roma's majority shareholder, James Pallotta, in New York in the last few days.
Garcia is rumoured to be earning €1.5 million-a-season.
"AS Roma announces that it has reached an agreement with Rudi Garcia, who will become the head coach of the first team,'' said a statement on the club's official website. "The two year contract will be formalised and deposited in the upcoming days.''
Garcia said: "I would like to thank Lille, its president, its fans with whom I've shared so much these last few years, and the club where I started my playing career and which enabled me to pick up my first championship win as a coach. Now I'm opening a new page. I'm proud to come into this big family that is Roma. I've come to win trophies.The fact I've been chosen by this club is also recognition of the training of coaches in France.
"We have to build a common project. We'll all do our utmost to make the fans happy. Roma has to get back into Europe. But when you play well, you have more chances of winning games. My playing style will be attacking."
Pallotta added: "We are very excited and confident that Rudi Garcia is the right coach for AS Roma. He is a proven winner with a great football mind who we believe fits in perfectly with our vision for the future. We welcome Rudi Garcia to AS Roma. ''
Roma chief executive Italo Zanzi commented: "He will continue to develop our existing talent base while giving us the best opportunity to win now. We are looking forward to this season more than ever.''
Lille president Michel Seydoux paid tribute to Garcia: "Our five years working together were extremely rich in sporting and human terms. I salute the work of the coach, his performances, and the human qualities of the man. Though the LOSC will continue to grow without Rudi, we will never forget he has contributed greatly to the club's development and he will always have a special place here."
Garcia, for whom the high point of his five-year tenure at Lille was the 2010-11 league and cup double, will be joined at the Stadio Olimpico by his two assistants, Frederic Bompard and Claude Fichaux.
The name of his replacement should also be known within the next two days, L'Equipe also reports, after Seydoux interviewed three potential successors in Paris on Tuesday.
Former Montpellier coach Rene Girard, 59, is favourite to take over at the Grand Stade, but Borussia Monchengladbach's Swiss boss Lucien Favre and Francky Dury, both 55, who guided unfashionable Zulte-Waregem to runners-up spot in the Belgian league last season, are also in contention after impressing Seydoux.