So much for the Reds being invincible in the cups. Phil Jevons, a former Liverpool fan and Everton player, stunned Merseyside last night with a 35-yard winner here that flew into Chris Kirkland's net just eight seconds from the end of extra-time.
Having endured relentless home pressure throughout normal time and fallen behind to Gary McAllister's 100th-minute penalty - awarded for hand-ball against David Beharall - the Mariners had scored the unlikeliest of equalisers just 13 minutes later when Marlon Broomes swept home Stuart Campbell's cross.
The 5,000 travelling supporters, delirious in celebration, paid special tribute to goalkeeper Danny Coyne who pulled off 13 saves of varying brilliance. The Fishermen left happy with the biggest catch in their history.
Since Lennie Lawrence won the first division's manager of the month award for August, the Mariners have sunk without trace. There were five wins in their first seven games, but their last victory came a month and seven matches ago with 18 goals shipped along the way.
That wretched form was hardly appropriate preparation for a trip to Merseyside, but they were impressive in the opening skirmishes with Jonathan Rowan busy and Jevons marauding across the home back-line and prompting an anxious Sami Hyypia to intercept.
Liverpool's success in this competition last season proved the catalyst for the glut of cup wins that followed. Their debt to the Worthington was recognised here with their strongest available line-up, although with a quartet of first-teamers crocked and Steven Gerrard suspended, Jamie Redknapp was surprisingly left to champ at the bit on the bench.
The midfielder's recovery from a long-term knee injury has comprised just two appearances this term and was expected to start here.His manager may urge patience, but the 28-year-old's contract expires next summer and his continued absence may rule out another.
Dietmar Hamann might have made way for Redknapp, but the German was soon linking with Jari Litmanen, with Paul Groves forced to intercept as he prepared to volley beyond Danny Coyne.
Vladimir Smicer's cut-back was then hammered goalwards by Litmanen, only for Danny Butterfield to block on the line. The midfielder repeated the trick to keep out Frode Kippe's glancing header seconds later but his third desperate clearance, from Litmanen's cross, was almost sliced into his own net.
Yet, that represented the visitors' closest shave of the first half, an achievement in itself given that Liverpool had not lost a domestic cup tie since January 2000 when another first division side, Blackburn Rovers, won here in the FA Cup.
Coyne sprawled to tip a McAllister free-kick around the post as Liverpool tried to avoid extra-time and Litmanen was brilliantly denied by Coyne as he volleyed towards the top corner.
LIVERPOOL: Kirkland, Wright, Hyypia, Carragher, Vignal (Kippe 21), Murphy, Hamann (Heskey 64), McAllister, Barmby, Litmanen (Redknapp 77), Smicer. Subs Not Used: Dudek, Berger. Booked: Hyypia. Goals: McAllister 101 pen.
GRIMSBY: Coyne, Beharall, Groves, Broomes, Gallimore, Pouton, Butterfield, Campbell, Chapman (Allen 103), Jevons, Rowan (Boulding 81). Subs Not Used: Coldicott, Ford, Ermes. Goals: Broomes 113, Jevons 120.
Referee: E Wolstenholme (Blackburn).
