Ayr then had Ross Robertson and Dean Keenan dismissed for second bookings before Campbell and Scott Allan had penalties saved by David Crawford.
Martyn Fotheringham tucked in Forfar's fourth penalty, Will Easton replied and Graham Gibson added a late header.
Forfar Athletic: Gallacher, McCulloch, Iain Campbell, Bolocheweckyj, Tod, Hilson (Martyn Fotheringham 70), Mowat, Allan (Brady 84), Deasley, Templeman (Gibson 83), Ross Campbell. Subs Not Used: McLean, Smith.
Goals: Ross Campbell 12 pen, Templeman 59, Martyn Fotheringham 81 pen, Gibson 90.
Ayr United: Crawford, Tiffoney (Taggart 62), Easton, Malone, Campbell, Trouten, Robertson, Keenan, McLaughlin, McKay (Reynolds 74), Roberts (Rodgers 73). Subs Not Used: McWilliams, Smith.
Sent Off: Robertson (68), Keenan (77). Booked: Keenan, Robertson, Easton, Campbell. Goal: Easton 89.
Ref: Colin Brown