Czech Republic's Euro 2012 campaign came alive thanks to two goals in the first six minutes against 2004 champions Greece.
Petr Jiracek scored the opener when he converted Tomas Hubschman's defence-splitting pass in the third minute.
Vaclav Pilar then grabbed his second goal of the tournament when he bundled home from two yards out.
Greece had a goal ruled out for offside before Fanis Gekas capitalised on a Petr Cech howler after the break.
It was the fifth goal Chelsea's usually reliable number one had conceded in this tournament, but fortunately for the 30-year-old he avoided further errors as his side held on for a vital victory.
Apart from their defensive naivety during the 4-1 defeat by Russia, Czech Republic's other failing was waiting until late in the game to demonstrate their potency in attack.
There was no such caution against the Greeks, as they catapulted themselves into a 2-0 lead inside six minutes.
Both were scored by Wolfsburg players. The first from the boot of wideman Jiracek, who ran in from the right, burst past the Greek defence, and slotted in Hubschman's beautifully-weighted pass.
The Greeks, who had to reorganise their defence coming into the match because of injury and suspension, were punished again three minutes later.
Arsenal's Tomas Rosicky fed in Theodor Gebre Selassie on the right side of the area. The full-back, who was a constant threat on the wing, pulled his cross back for Pilar, who beat two defenders to the ball and directed his shot in with his thigh.
There were further woes inflicted on Greece when veteran keeper Kostas Chalkias came off with an injury to be replaced by Michalis Sifakis in the 23rd minute.
The PAOK Salonika man had barely got into position before he was called to push away Rosicky's 25-yard drive.
The Greeks' only threat of the half resulted in the ball hitting the back of the net, but Giorgos Fotakis's header was controversially ruled offside. The replay seemed to suggest he was level.
Fotakis was replaced by Gekas after the break and, like in the first match against Poland when Dimitris Salpangidis, who started today, came on in the second half and made a difference, the change gave Greece an early boost.
On this occasion, Cech played a big part in goal when confusion between himself and his defender Tomas Sivok caused him to fumble a tame cross. Gekas had the easy task of passing into an empty net.
Greece brought on Olympiakos's Kostas Mitroglou to bring the number of forwards in their XI to four with 20 minutes remaining, but they seemed devoid of ideas against a flaky Czech defence.
The defeat leaves the Greeks needing victory against Russia to stand a chance of progressing, while the revitalised Czechs will face co-hosts and neighbours Poland for a possible do-or-die Group A finale.