The Hornets cruised to an impressive 3-0 win away to Newcastle United on Saturday as Will Hughes and Andre Gray scored either side of a DeAndre Yedlin own goal.
Silva's side have now won two straight in the Premier League and, with Richarlison continuing his eye-catching form, appear ready to take it to the Red Devils at Vicarage Road.
The Portuguese, who continues to be linked with the vacancy at Everton, said Watford fully deserved to take three points into their midweek match.
"We had very good moments. We scored the first goal through something we planned," Silva told the BBC.
"We knew [Newcastle] were strong in the long balls and first and second balls and I think we controlled them really well.
"It is important for our players to play with this confidence. It is important for them to rest now and we have a hard game against Manchester United on Tuesday."
7 - No player has been involved in more away goals in the Premier League this season than Richarlison (4 goals, 3 assists). Talent.— OptaJoe (@OptaJoe) November 25, 2017
While Watford are safe in eighth, Newcastle have now lost four successive Premier League fixtures and have slipped back to 13th in the table.
However, Magpies boss Rafael Benitez cautioned against panicking.
"We have to realise where we are, what we have and where we want to be," he said.
"I have said before it is going to be a tough season and we have to keep working as hard as possible."