Ighalo scored twice in the victory to take his tally for the season to 12 as Watford sit seventh in the Premier League with 28 points from 17 games.
“Some people may have been surprised,” Ighalo said.
“But I walk out with this team every week and we work hard for each other, we run for each other and fight for every ball.
I’m not surprised any more. But we need to keep going like this.
“This result may make top teams respect us more and not just treat us as a promoted side who are not going to be around the Premier League for long time.”
The former Granada of Spain striker added that the players were not taking anything for granted despite close to securing a spot to play in European football competition.
“We’re not getting carried away,” the 26-year-old said. “We can’t think too much about being one point off the Champions League places because our first target is to collect 12 more points to preserve our Premier League status.
“That’s our objective. We’re not safe yet. We have only 28 points and our aim is to battle against relegation. If we reach 40 points, we thank God for anything that comes after that.”