City go into this Saturday's fixture looking to extend their unbeaten start to the league campaign to thirteen games against an Oxford side who suffered their first home defeat of the season to AFC Wimbledon last Sunday.
Despite that recent defeat for The U's though, McCall is still very wary of Oxford's threats and is expecting a challenging encounter for his players at the Kassam Stadium.
Looking ahead to the game, McCall said: "This has the potential to be as tough an away game as we'll have had so far (this season), and we've already had some tough ones.
"I think they were a bit unfortunate last weekend. If they would have won, I believe they would have been in and around the top six.
"AFC Wimbledon did well in the match but I think it could have been a different story if one or two decisions had gone Oxford's way.
"They have some very good individuals players, key players who can hurt anyone at this level, and the place will still be buzzing following their promotion at the end of last season.
"We know what challenges this game will bring us and we will have to be ready for that.
"As normal, we have to focus largely on ourselves. Our away performances of late have been very good but we are still expecting a difficult game.
"I'm sure Oxford will be trying to become that first team to beat us - they will want to win as they would do any other game - but we can't look at it in that way too much.
"We can only focus on ourselves, treat it as a normal game, and try to get that next three points.
"If we want to come home with those three points though, we know we will have to be at the top of our game.
"There will be times when we can get the ball down and play our football, and there will be times when we have to battle, scrap and defend manfully.
"We have to figure out a way to ensure we come out on top in all of these situations."