As previously highlighted, Olympiacos will be looking to come out of the blocks quickly, given their home advantage.
When they played against Leverkusen in the Champions League group format, they were 1-0 up inside two minutes, and 2-0 up by half-time. Inevitably, this altered the game state from a very early point in the match, which is possibly the reason Olympiacos only ended up having two corners, both of them unsurprisingly coming in the first half.
Olympiacos’ corner numbers in Champions League home matches haven’t been that high, but I think this is somewhat of a statistical anomaly. In home matches against Real Madrid and PSV, they managed exactly 18 shots and exactly three corners in both matches. Crucially, this shows they can be very competitive from a territorial standpoint, and those low corner numbers are definitely not a reflection of the territory they had.
Any variable that involves Leverkusen going ahead or Olympiacos failing to take the lead should leave a favourable game state for home corners.