According to reports, a deal was struck late on Friday for the Brazilian to join Russian champions Zenit.
23-year-old Wendel will sign a five-year contract with his Zenit medical scheduled for Monday.
Sporting signed Wendel from Fluminense for around €9m at the start of 2018.
His performances led to him being followed by Napoli, while CSKA Moscow tried to sign him last season.
The Brazil under-23 international has been one of the few highlights in Sporting’s side recently.
Wendel has played 79 games in all competitions for Sporting, scoring six goals.