The 25-year-old's form this season has drawn the attention of the Premier League duo, with the striker scoring 20 goals and registering 12 assists in 36 appearances across all competitions.
However, Portuguese outlet Record reports that Benfica are close to agreeing a new contract which would increase his buyout clause.
Vinicius's current contract already runs until 2024 and contains a release clause of €100m (£87.8m), but Benfica are keen to raise that to €120m (£105.4m).
Speculation earlier this year suggested that Benfica may be willing to consider offers of around €60m (£52.7m), though, and the report claims that the Brazilian wants a move to the Premier League.
Vinicius only joined Benfica from Napoli in a £15m deal last summer, but has seen his value skyrocket after directly contributing to a goal every 87 minutes in the league. body check tags ::