The Teessiders are in danger of slipping out of the top six after taking just four of the last 24 points on offer, and 30-year-old McManus, who returned to the side for the first time since October in Tuesday night's 0-0 draw at Burnley, is confident they have what it will take to turn their form around.
He told the club's official website: "Every game between now and the end of the season is a massive game.
"But look at the quality we have got all over the pitch - we have nothing to fear.
"I have always had a tremendous rapport with the fans, the staff and players here. I have loved my time here and hopefully I can play my part between now and the end of the season. If I can help in that in any way, that is what I want to do.
"You don't feel like a footballer when you are not playing. You want to be playing week in, week out to be an important squad member, and I'm certainly no different."