Manchester United scouts watched on as Benfica defeated Vitoria 1-0 in the Portuguese Primeira Liga on the weekend.
According to reports in Portugal, the talented midfielder impressed the Red Devils onlookers with his performance in the 1-0 victory which came courtesy of a 74th-minute goal from the 18-year-old.
The United scouts reported back to Louis van Gaal with plenty of positivity, further heightening the club's interest in his services, as rumours of a potential January swoop continue to rumble along.
Sanches has been at Benfica since he was 11 and has this season broken into the first team having made eight league appearances two in the Champions League for Rui Vitoria's Eagles.