"With the way the semi-final draw has worked out there is a massive incentive there," said Anscombe.
The winner of the game will then have home country advantage in the semi-finals at the end of April against either Toulon or Leicester Tigers.
"The eight teams in the quarter-finals are all high quality sides, so there was never going to be such thing as a favourable draw," he added.
"It's disappointing not to be at home but we dropped our guard by not beating Northampton at Ravenhill and that has cost us.
"Hopefully we will get our injured players back for the quarter-final. It is two and a half months away, so a lot is going to happen between now and then.
Meanwhile, there is that fascinating clash with McCall, who lifted European club rugby's most coveted trophy with Ulster's current Director of Rugby David Humphreys against Colomiers at Lansdowne Road in 1999.
McCall also coached Ulster between 2004 and 2007 and led the Province to the Celtic League title in 2006.