Renowned as a speedy attacker, Glennon took up his station in the left corner at the throw-in where, as expected, Ciarán Hyland took up the marking duties.
Once the game began, though, he decamped to the middle and while Hyland often prospered, Glennon got on a lot of ball, even if it seemed odd to see him in possession behind his own half-back line at times.
When it counted though, he was the man on the spot to set up a Leinster semi-final pairing with Louth that would not have been predicted by anyone last week.
An eventful day began with a 15 minute delay to the start on the advice of Gardaí as thousands queued for tickets outside and the Leinster Council booths reportedly ran out of change.
In the end, it was agreed to take cash at the stiles but with the O’Connor Park staff not having been expected to fulfil such a duty, they too were without change and had to accept whatever many of the estimated 8,300 patrons had to offer.
Once the game got under way, there was plenty of action too, especially in the final ten minutes, which produced three red cards in two minutes, Wicklow’s 70th-minute equalising goal and then Glennon’s dramatic strike.
In one fell swoop, the agony of a winless league campaign that ultimately led to Brendan Hackett’s departure as manager was history. But that was no surprise to Wicklow boss, Mick O’Dwyer.
“Don’t talk about the league at all,” he said. “The league is irrelevant when it comes to championship football. They have a lot of experienced players on that team; men who won minor All-Irelands, U21 All-Irelands and a Leinster (senior) title.”
Hackett’s replacement, Pat Flanagan took on the role as caretaker boss six weeks ago and Glennon and Dessie Dolan, who was introduced to quite an effect in the 44th minute quickly returned.
“I’ve said all along I’ve huge belief in all those guys” said Flanagan. “They were always going to put on a performance today. They had to. After what happened, they were going to stand up. There’s an awful lot of proud guys in there. All they needed was the belief.”
Wicklow dominated possession in the first half, due largely to the brilliance of James Stafford, but it was Westmeath who led 0-5 to 0-4 at the interval.
They carved out a 0-4 to 0-1 lead by the end of the opening quarter, recovering well from conceding an early point to Tony Hannon from a free after a brilliant flick by Kieran Martin to dispossess the Wicklow man was inexplicably deemed a foul by the overly fussy Michael Collins.
The magnificent Martin Flanagan, Michael Ennis and a Paul Greville (two) put the Maroons in a strong possession but Stafford continued to hold sway and Wicklow gradually clawed themselves back into it.
Darren Hayden came forward for their only score from play of the half and Hannon recovered from some previous poor place-kicking to convert two more frees, the second from 47m to leave just the minimum between the sides.
Where Wicklow might have been expected to push on, instead it was Westmeath who took a grip on proceedings.
Man of the match Conor Lynam started a run of four successive points, after dummying Brian McGrath and arcing over neatly. Doran Harte finished it after tremendous work from Flanagan to set him up.
With 14 minutes remaining Westmeath led by five but Wicklow continued to plug away and when Hyland pointed with just three minutes left, the gap was down to three.
By that stage, there had been a crazy spell of three dismissals in two minutes, all for second yellow cards. Westmeath’s John Gaffey was first to go in the 60th minute, followed quickly by Leighton Glynn, who had only collected his first yellow seconds beforehand.
Westmeath midfielder David Duffy was sent marching in the 62nd minute and we awaited the Wicklow onslaught.
The goal came on the 70th minute as Stafford’s shot was blocked and Furlong’s kick off the ground stopped by Connaughton before Paul Earls slamming home the rebound from a tight angle.
But there was one last roll of the dice and it came from Glennon, who capitalised on a blocked attempted clearance by the otherwise excellent Steven Kelly to snatch the winner.
Scorers for Westmeath: C Lynam, P Greville, M Flanagan (1 45) 0-3 each; D Glennon 0-2; M Ennis, D Harte, P Bannon, D Dolan 0-1 each.
Scorers for Wicklow: T Hannon 0-5(fs); P Earls 1-1; S Furlong 0-2 (1f); C Hyland, D Hayden, N Mernagh 0-1 each.
Subs for Westmeath: G Egan for Gaughan (33); D Dolan for Smyth (44); T Warburton for Martin inj (52).
Subs for Wicklow: J Flynn 7 for Travers inj (18); S Canavan 7 for McGrath (62).
Referee: M Collins (Cork).