Usuthu, who narrowly avoided relegation last term, are joint-top of the Premiership standings with 11 points from six games.
"I think we’ve grown in stature and that’s the most important thing," Rosslee told his club's official website ahead of Saturday's Telkom Knockout last-16 tie with Free State Stars.
"I don’t think at this point in time we are really fazed by the opponents; we are more focused on the job that we’ve got to do."
Regarding the upcoming tie with Ea Lla Koto, Rosslee expects a physical affair at Goble Park Stadium.
"It’s an extremely tough game. Goble Park is a small field and Free State Stars are a very physical side.
"We’re going to have to mix it up and we have to make sure that we are really competitive on the day. We’ll have our work cut out for us.
"Obviously the game is away from home but we don’t want to take away from the good work and the style we have been playing up until now.
"Free State Stars approach the game in a certain way and we want to continue playing the way that we want to play. But there will be one or two different aspects that we want to address due to the fact that it is a small park and to the style that Stars do play.
"We’ll make sure that we have that covered and make sure that we are competitive. Whether it’s the league or a cup game, we have to make sure that we show our mettle."