Wales' Euro 2008 hopes suffered a major blow as they were soundly beaten by an impressive Slovakia side in Cardiff.
Jones will have a hard time forgetting his 50th cap
Dusan Svento slotted home the first to kick off a horror afternoon for keeper Paul Jones on his 50th appearance.
A fluffed Jones clearance saw Marek Mintal score from 35 yards before Gareth Bale responded with a free-kick.
Mintal's 25-yard screamer put Slovakia back in control, before Miroslav Karhan's chip and Robert Vittek's cool finish compounded Welsh misery.
The Millennium Stadium hammering was Wales' worst home defeat since a 7-1 loss to England in Wrexham in 1908, and manager John Toshack will have a hard job to lift morale before Wednesday's game with Cyprus in Cardiff.
Wales enjoyed a bright start as a sublime Jason Koumas ball from midfield got Bale to the by-line, the full-back's cross failing to reach an unmarked Robert Earnshaw in the box.
The visitors soon made Wales pay, possession falling to Vittek on the edge of the box where the FC Nuremberg forward had the skill to turn Lewin Nyatanga before delivering a beautifully weighted ball across the face of goal.
Svento opened the scoring for Slovakia
Svento nipped in ahead of Richard Duffy at the far post to fire back across Jones, the keeper's despairing flap unable to keep the ball out.
Earnshaw had an immediate chance to reply from a ball over the top, his lob well saved by Kamil Contofalsky.
Craig Bellamy just failed to find Earnshaw with a ball from the by-line, but every time the east Europeans broke at pace the home side's inexperienced and unfamiliar back line looked vulnerable.
Bellamy - captaining his country for the first time in a week where he faces an assault trial in Cardiff - had the ball in the net on 30 minutes, but saw his effort ruled out for offside.
A lot of players out there aren't getting regular club games
Wales captain Craig Bellamy
Jones - with the number 50 and a dragon shaved into his hair to celebrate his cap landmark - then made one of the worst mistakes of his long international career.
A weak clearance kick under no pressure went straight to Mintal, and the FC Nuremberg striker fired a snap 35-yard shot into the empty goal.
Wales hit back as Koumas was fouled just outside the box, allowing 17-year-old Bale to curl a beautiful left-footed free kick into the top right corner for his first international goal, making him Wales' youngest-ever scorer.
But home hope was extinguished within a minute as Mintal latched onto an innocuous-looking ball to drive a stunning 40-yard shot past Jones.
Bellamy had a chance to narrow the gap shortly before the break, but his shot slid narrowly wide.
Bale's celebrations of his first Wales goal were short-lived
The home side replaced Earnshaw with Paul Parry at half-time, but Jones' nightmare continued as a Jan Kozak short corner to the unmarked Karhan ended with the midfielder curling a 30-yard goal over the hapless keeper.
The 39-year-old QPR veteran had no chance with the fifth, Svento skinning Duffy down the left and delivering a ball to the feet of Vittek, who made no mistake with the finish.
Joe Ledley's introduction for Rob Edwards and the switch to a flat back-four steadied Wales, and Bellamy went close with two chances.
But the poor home performance leaves Welsh qualification hopes in tatters after just two games of their campaign.
Wales: Paul Jones, Duffy, Bale, Gabbidon, Nyatanga, Robinson, Edwards (Ledley 58), Koumas, Simon Davies (Cotterill 88), Bellamy, Earnshaw (Parry 45).
Subs Not Used: Price, Morgan, Vaughan, Crofts.
Booked: Koumas, Simon Davies.
Goals: Bale 37.
Slovakia: Contofalsky, Kozak, Kratochvil, Martin Petras, Varga, Karhan (Krajcik 67), Mintal (Hodur 71), Vittek (Holosko 77), Peter Petras, Svento, Durica.
Subs Not Used: Hajduch, Valachovic, Had, Sapara.
Goals: Svento 14, Mintal 32, 38, Karhan 51, Vittek 59.
Ref: Dick Van Egmond (Holland).