The three-peat is still on for Peterborough United thanks to Donay at the death

The midfielder supplied a cool finish after fellow replacement Harry Leonard had prodded him through on goal just as thoughts were turning to a winner-takes-all penalty shootout.

Posh, who have won this competition in each of the last two seasons, deserved to go through for the strength of their finish as they came close to scoring on a handful of occasions before O'Brien-Brady struck, but it wasn’t a game or a performance that will live long in the memory of the visiting fans who made up part of a crowd of just 924.

The priority for new Posh boss Luke Williams was signposted by his team selection. Only three who started the demolition of Wimbledon on Saturday started in Sussex. They were central defender Tom O’Connor and wingers Abraham Odoh, a hat-trick hero on the this ground last season, and Kyrell Lisbie, a hat-trick hero in the last Posh match in this competition.

Young central defender Fabian Claxton was handed a senior debut as manager Luke Williams changed his goalkeeper and three of his defenders. James Dornelly and Carl Johnston returned as full-backs with the latter on the left with Tom Lees, Peter Kioso, Harley Mills and ‘keeper Alex Bass dropping out of the squad altogether.

Transfer-listed Ryan De Havilland was given a game in midfield, while Klaidi Lolos started against a former club behind Jimmy-Jay Morgan who was the lead striker with Gustav Lindgren surprisingly left on the bench. Crawley fielded former Posh striker Kabongo Tshimanga.

It was no surprise to see a first-half in which Posh lacked any sort of cohesion. They worked their way into a few promising crossing positions, but they either dithered disappointingly or went backwards fatally.

Crawley were better for much of the half, but struggled to get efforts on target. A first-minute header from Ryan Loft had to be handled by Posh keeper Vicente Reyes, but Jack Roles and Josh Flint shot wide when well placed.

Posh didn’t have a shot at goal until the 30th minute when Lisbie’s dribbler just about reached goalkeeper Harvey Davies, but the visitors had the home ‘keeper to thank for a lead they didn’t deserve 10 minutes before the break. Davis was caught in possession by Morgan who then tapped into the empty net.

Crawley should really have been awarded a penalty on the stroke of half-time when Johnston clattered into Tshimanga, but instead the foul went the way of Posh.

Posh had a strong wind at their backs in the second-half and appeared to be coasting to victory as the home side struggled to locate their shooting radar, but poor marking at a corner enabled Geraldo Bajrami to head home a 73rd minute corner.

That was the signal for Posh to pepper the home goal. Goalkeeper Davies made amends for his earlier blunder to superbly tip a quite brilliant free-kick from Brandon Khela onto the crossbar. Davies then thwarted Lindgren after the Swede had raced clear onto a Ben Woods through ball and he was out quickly to smother a shot from Odoh who really should have passed.

When a defender headed a Woods corner onto the crossbar in the 93rd minute it looked a spot-kick contest, but then Leonard sprung O’Brien-Brady to win the night.

Williams is currently a manager with a Midas touch. That’s three wins in three matches in three different competitions for the new boss.

Posh: Vicente Reyes, James Dornelly, Fabian Claxton (sub Lucca Mendonca, 59 mins), Tom O’Connor, Carl Johnston, Brandon Khela (sub Harry Leonard, 84 mins), Ryan De Havilland (sub Ben Woods, 71 mins), Abraham Odoh, Klaidi Lolos (sub Donay O’Brien-Brady, 59 mins), Kyrell Lisbie, Jimmy-Jay Morgan (sub Gustav Lindgren, 71 mins).

Unused subs: Bastian Smith, Archie Collins,

Crawley: Harvey Davies, Geraldo Bajrami, Harry Forster (sub Ade Adeyemo, 46 mins), Josh Flint (sub Jude Robertson, 59 mins), Jack Roles, Ben Radcliffe (sub Charlie Barker, 46 mins), Kyle Scott, Joy Mukena, Fate Kotey, Kabongo Tshimanga, Ryan Loft.

Unused subs: William Heater, Max Anderson, Reece Brown. Tola Showunmi.

GOALS: Posh – Morgan (34 mins), O’Brien-Brady (90 + 4 mins).

Crawley – Bajrami (73 mins).

Cautions: Posh – Odoh.

Crawley – Scott (foul), Baxter (foul).

Referee: Carl Brook 7

Attendance: 924 (212 Posh).