The Hornets were tipped by many to be among the candidates for relegation this term but sit unbeaten after four games with two wins and two draws, a run that has seen them claim an unlikely fourth-place spot in the primitive league table.
Janmaat was on the scoresheet yesterday as the Hornets managed a 2-0 victory at Southampton and, speaking to reporters after the final whistle, the Dutchman predicted more good things to come.
"We're unbeaten with eight points from four games so it's a fantastic start to the season," he told the Watford website. "We have got to continue like this and on Saturday we have Manchester City at home and a great opportunity to try to stay up with them.
"We are playing with a lot of confidence at the moment. We have a good team, some good signings, a lot of strength in the team and pace up front.
"I think we can threaten a lot of teams with the way we are playing and we can have a great season."
Watford have managed successive finishes of 13th and 17th following their return to the top flight in 2015.