Both Serie A sides are in talks with Cagliari about signing the defender this summer, his current club's transfer chief has confirmed
The defender is widely expected to move on before the start of the new season and a host of clubs have been linked with the centre-back.
Marroccu has confirmed talks have been held with both Juve and Lazio and it is unclear where the 27-year-old will start the 2014-15 campaign.
"We are in negotiations with both Lazio and Juventus," he told Il Messaggero.
"The Juve interest has been going for some time and did not coincide with the arrival of new Juventus coach Massimiliano Allegri.
"At the moment we cannot say whether one club or the other has the advantage. Negotiations will continue by phone, so no meetings are planned over the next few days."
The Italy international has also been linked with Premier League sides Tottenham and Southampton.