Nearest rivals Swindon Town appeared poised to take top spot as they crossed to a 3-0 win at 10-man Notts Couny - Andy Williams netting a first-half brace before Liam Noble elbowed Nathan Thompson to see red and Massimo Luongo sealed the points.
But centre-back Ayling finished clinically from Luke Freeman's corner to keep City a point clear of Swindon at the summit and leave Crawley a place and two points above the drop zone.
Rochdale are sixth having been on the right side of a similarly comprehensive 4-1 scoreline at Colchester United.
Keith Hill's team are level on points with Oldham, Notts County and Peterborough United - the latter winning 2-1 at Leyton Orient to ruin Fabio Liverani's first game in the Brisbane Road hot seat.
Scunthorpe United are two points above the relegation zone after a 2-1 win over basement boys Crewe, a third win in four matches for Mark Robins' men, and Luke Norris scored both goals as Gillingham won at Doncaster Rovers by the same margin to remain level with United and a point behind their weekend opponents.
