While the visitors occupy third spot in the Scottish Championship, the home side are second in Scottish League One, ensuring that a minnow will reach the last four.
Match preview
Earlier this week, Falkirk saw an 11-match unbeaten run in all competitions come to an end as they lost out away at Dunfermline.
The result was particularly damaging as it allowed the leaders to move eight points clear at the top of the third-tier standings, but John McGlynn will want to forget about league matters ahead of what is a massive game for the club.
En route to the quarter-finals, it cannot be disputed that the Bairns have had some luck with the draw, playing Wick Academy, Alloa Athletic and Darvel.
However, each victory has come away from their home ground and 13 goals have been netted in the process, the strikes being shared around the team with Gary Oliver top-scoring with three.
On the league front, Falkirk have posted five consecutive wins on familiar territory, and they will be backing themselves to upset their higher-league opponents.
From Ayr's perspective, they have endured a marginally tougher route to the last eight, although they too have avoided playing a top-flight team.
Pollok, Cove Rangers and Elgin City have been dispatched, the latter by a 4-1 scoreline after extra time after Ayr had equalised in the final minutes of normal time.
Lee Bullen's side have been inconsistent in the league, however, with just three victories coming from their last 10 encounters in the second tier.
Although they still hold third place in the standings, there is now an eight-point gap to leaders Queen's Park.
Falkirk Scottish Cup form:
Falkirk form (all competitions):
D
W
W
W
W
L
Ayr United Scottish Cup form:
Ayr United form (all competitions):
L
D
L
D
L
W
Team News
Despite suffering defeat at Dunfermline, McGlynn will likely stick with the majority of the team which started that game.
Maksym Kucheryavyi and Craig McGuffie will both feel that they are in contention for appearances, although Liam Henderson may take the spot of the former in the Falkirk XI.
Josh Mullin will be assessed by Ayr after he missed the last game due to a nasty cut on his foot.
Chris Maguire is on hand to deputise if required, but Daire O'Connor is available after serving a suspension in the league.
Falkirk possible starting lineup:
Kinnear; Rowe, Donaldson, Mackie, McCann; Henderson, McGinn; Morisson, Nesbitt, Kennedy; Oliver
Ayr United possible starting lineup:
Albinson; McAllister, Kirk, McGinty, Reading; Dempsey, Dempsey, McAlear, O'Connor; McKenzie, Akinyemi
We say: Falkirk 1-2 Ayr United
Despite the difference in divisions, this feels like a 50-50 tie when you consider the nerves and tensions which will be on show. Although Ayr arguably have the superior quality, we are backing Falkirk to use home advantage in their favour and secure a narrow victory.