Nigel Pearson made five changes for this trip to the south coast with Morgan, Moore, Marshall, Drinkwater and Schlupp returning to the starting XI.
Gus Poyet had to bring on an 11th minute subs when Lua Lua came on for Buckley.
City looked much improved from the Barnsley outing and had the best of the first half.
King sent one effort across goal narrowly wide; while Nugent’s low drove was saved by Kuszczak. with a low effort from 20 yards as City were able Brighton’s best first half moment came after 30 minutes when Calderon’s header was blocked by the flicked up heel of Drinkwater on the line before Bridcutt fired the follow up well over.
City then went close up the other end, Schlupp squaring for King whose side-footer from inside the area smacked against the bar.
Schlupp then had a one-on-one with Kuszczak but he shot straight at the keeper.
City kept up their improved form in the second half: Konchesky’s cross from the left, eventually finding Moore at the far post but he put a difficult chance over. King then attempted a curling effort Kuszczak parried away.
De Laet then replaced Marshall on the right wing.
In the 70th minute Lua Lua’s pace took him round Moore but Ulloa mishit his shot inches wide.
Two minutes later City finally broke the deadlock. Moore’s throw from the right, was flicked on by De Laet and James reacted swiftly to gather the ball and despatch it past Kuszczak from close in.
Kane and Wood were immediately introduced for Nugent and Schlupp as City attempted to see out the closing stages and defend their vital lead.
Unfortunately this resistance only lasted until the 87th minute when Lua Lua cut in from the left and launched an effort from the edge of the area that beat Schmeichel for pace.
The game that City had to win ended in a 1-1 draw, which saw City remain outside the play-off frame, and was a huge disappointment for the 2,000 travelling fans.
Brighton: Kuszczak, Calderon, Greer, Upson, Bridge, Bridcutt, Lopez (Vicente 54), Hammond, Buckley (Lua Lua 11), Ulloa, Orlandi (Barker 78). Unused Subs: Ankergren, El-Abd, Painter, Crofts.
Leicester: Schmeichel, Moore, Morgan, Keane, Konchesky, King, James, Drinkwater, Marshall (De Laet 60), Nugent (Kane 72), Schlupp (Wood 72). Unused Subs: Dyer, Logan, Wellens, Knockaert.
Referee: Jonathan Moss (West Yorks). Attendance: 28,493.