McCall's men will be hoping to hand Edinburgh their second straight league defeat, after lost to Leinster last Saturday. Ulster are away in their next three league fixtures and the importance of the next three games, which McCall is referring to as Ulster's "mini season", cannot be played down.
"To start the season with a game against a strong and physical side like the Ospreys, and then have a run of three away games back-to-back is going to be a challenge. But with the group of players we have, we are confident we can emerge from these four games with points on the board," McCall said.
The Ulster squad is missing 10 players due to the World Cup and with another seven players injured and unavailable for selection this weekend, this makes the coach's job even trickier.
McCall acknowledges that the injuries the Ulster squad have suffered over the last few months have been very frustrating, adding: "The spirit and character amongst the squad has been really pleasing, and some of the younger players have emerged far more than any of us thought."
But he recognises that the positive to come out of the current injury situation, along with the players being away at the World Cup, is that "the younger players in the squad now have the opportunity to step up to the plate."
ULSTER: Bryn Cunningham; Simon Danielli, Tommy Bowe, Seamus Mallon, Mark McCrea; Niall O'Connor, Kieran Campbell; Justin Fitzpatrick, Nigel Brady, Tom Court, Justin Harrison, Ryan Caldwell, Matt McCullough, David Pollock, Roger Wilson (capt).
Replacements: Matt Miles, Declan Fitzpatrick, Tim Barker, Kieron Dawson, Paul Marshall, Adam Larkin, Mark Bartholomeusz.
Unavailable due to injury:
Stuart Philpott, Neil Hanna, Jarlath Carey, Neil McMillan, David Humphreys, Paul Steinmetz, Paul McKenzie