Former Premier League player Greg Halford scored on his Waterford debut as the 10-man Blues eventually won an incredible game at Athlone Town on penalties to reach the FAI Cup second round.
Glen McAuley's incredible 123rd-minute strike for Athlone also lit up a dramatic night in the midlands.
Halford, formerly of Sunderland and Nottingham Forest and mostly recently of Southend in League Two, came on during the second half in Athlone Town Stadium after becoming Marc Bircham’s ninth signing of the transfer window.
OH MY GOD! ??— SSE Airtricity League (@SSEAirtricityLg) July 23, 2021
Absolutely incredible goal by Glen McAuley to score his hat trick and equalise for Athlone Town, the game goes to penalties! ??@AthloneTownAFC 4-4 @WaterfordFCie
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One of those additions, Anthony Wordsworth, scored his first Blues goal with a well-placed 20-yard shot on 40 minutes.
Shane Griffin made it 2-0 victory on 52 minutes but Wordsworth was sent off after two yellow cards with 20 minutes left to give Athlone hope.
Former Liverpool youth McAuley slotted home a penalty five minutes later after a handball by George Forrest and Stephen Meaney levelled it up on 82 minutes.
McAuley looked to have won it with another spot-kick in the final minute. However, Halford headed home in stoppage-time to lead to extra-time.
Athlone boss Adrian Carberry was also sent to the stands, before George Forrest looked to have won it for Waterford when he scored in added time at the end of extra time.
Incredibly, McAuley shot from the halfway line at the resulting kick-off to seal a hat-trick and send the game to spot-kicks.
Paul Martin saved penalties from Jack Reynolds and Dylan Hand to secure a 4-2 win for Waterford that was as hard-earned as they could possibly have envisaged.
UCD sank First Division high-fliers Shelbourne 2-0 thanks to a strong second-half showing.
Colm Whelan broke the deadlock for the hosts with a penalty in the 56th minute, with Harvey O'Brien heading home the clincher nine minutes from time.
Wexford were convincing 3-0 winners against Cabinteely at Ferrycarrig Park.
The tie was wrapped up by half-time as they blitzed the visitors in the opening period. Kyle Robinson put them ahead in the 34th minute after good work from Jack Doherty.
Doherty made it two five minutes afterwards when he drilled home a penalty and then Jack Moylan bagged another just before the break with a brilliant run and finish.
Kilnamanagh powered past St Kevin's 4-1 in the battle of the Leinster Senior League teams.
Kilnamanagh enjoyed the perfect start when Dean Clarke pounced on a defensive error with just seven minutes on the clock.
Kevin's equalised through Jordan Cromwell in the 20th minute but Sean Byrne (54), Gary McCabe (60) and a lovely goal from Clarke (78) sent Kilnamanagh through.
The night's other non-league tussle went the way of Maynooth University Town who eased past Malahide United 4-0.
Paddy O'Sullivan's first-half hat-trick (17, 32, 43) set them well on the road to victory, with Jackson Ryan making absolutely sure of it 17 minutes from the end.