The 19-year-old has already won three senior caps for the national team but has to dislodge club-mate Karen Bardsley as City’s first choice as well as at international level.
Bardsley missed the Manchester Derby victory on the opening day through injury, and Roebuck took her opportunity - keeping a clean sheet and making an outstanding close-range save from Jane Ross.
City’s keepers are firm friends away the pitch but competitive on it, and Roebuck is determined to become first choice for club and country.
“I can only focus on myself. I've done that even when I'm in competition with KB, obviously,” she said.
“The aim for me is to be England's number one. That's obviously a really difficult task because there's other top quality goalkeepers in England.
“But I just focus on myself. I can only control what I can control and if I keep performing week in and week out then hopefully it gets noticed and puts me in the best position.”
Roebuck is taking advantage of working at City’s Etihad Campus, where both senior teams train, to take on advice from Pep Guardiola's goalkeeping coach Xabi Mancisidor and Ederson to help improve her game.
Like Ederson, Roebuck is confident with the ball at her feet and has watched and chatted to the Brazilian on the training ground.
“Their goalkeeper coach Xabi is always coming across and contributing, giving us ideas,” she said.
“It’s a really good working relationship and that reflects well on the club in general.
“I've grown up playing outfield and it comes a bit more naturally to me to play with my feet.
"I think it's the philosophy throughout the club and I've been here since I was 15 so for the past four years, it's really been embedded in me.
“It obviously helps and I've got great players around me to help that.
“We see them train and we walk around. It's just the environment itself, it's more just natural. But I think that's what's really special about the club.”
Roebuck’s save and a stunning 25-yard winner from Caroline Weir were the standout moments as City won the first-ever Manchester Derby in the Women’s Super League in front of a record crowd of 31,213.
Newly-promoted United were the better side in the first half and Roebuck admits her team-mates were not happy with the opening 45 minutes.
“We knew the first half wasn't good enough,” she said. “So myself, I was happy I could give that moment for the team.
“Second half, we came out and kind of turned the screw and picked up the tempo, which we should have known from the first half, but it just didn't happen and credit to Man United because they put a great performance in.”