UPDATE 2-Telecom Italia chief quits as Vivendi tightens grip - sources
* Resignation to be formalised in two to three days - source
* Flavio Cattaneo favourite to succeed Patuano - sources
* Departure seen as sign of growing Vivendi influence (Recasts with details, Vivendi no comment)
By Agnieszka Flak and Danilo Masoni
MILAN, March 19 (Reuters) - Telecom Italia Chief Executive Marco Patuano is stepping down, four sources close to the matter said on Saturday, ending weeks of speculation about his future as top shareholder Vivendi tightens its grip.
Patuano's resignation will be formalised in the next few days, a fifth source said. Patuano, 51, whose mandate was due to run for another year, was not available for comment.
His relations with Vivendi have been tense since the French media company took a stake of just over 8 percent in Telecom Italia in June, a source close to the matter has said.
Vivendi got the stake as part payment for selling Brazilian broadband company GVT to Spain's Telefonica, which at the time was Telecom Italia's biggest shareholder.
Since then, the French company headed by tycoon Vincent Bollore has tripled its stake in Telecom Italia to 24.9 percent, secured four board seats and pressured Patuano to cut costs at home, and also decide what to do with its Brazilian business. Continuación...