In this talk I will present the confirmation and follow-up characterization of a transiting substellar object detected by TESS. Ground-based photometric and spectroscopic follow-up from different facilities, obtained in the context of the WINE collaboration, confirmed the substellar nature of TIC4672985 b, a massive gas giant in the transition between the super-Jupiters and brown dwarfs mass regime. From the joint analysis the following orbital and physical parameters were derived:  P = 69.0480 +/- 0.0005 d, Mp = 12.74 +/- 1.01 M_jup,

Rp = 1.026 +/- 0.067 R_Jup and e = 0.018 +/- 0.004. In addition, the RV time series revealed a significant trend at the ∼350 m/s/yr level, which is indicative of the presence of a massive outer companion in the system. TIC 4672985 b is a unique example of a transiting substellar companion with a mass above the deuterium-burning minimum limit, located beyond 0.1 AU and in a nearly circular orbit. These planetary properties are difficult to reproduce from canonical planet formation and evolution models. Finally, I will present thermal evolution models with different internal composition, that match the current radius and age of this object.