Republic of Ireland 1 Croatia 3
REP IRELAND: Given, O''Shea, St. Ledger, Dunne, Ward, McGeady (Cox 54), Whelan, Andrews, Duff, Doyle (Walters 53), Keane (Long 75).
Goal: St. Ledger 19.
CROATIA: Pletikosa, Srna, Corluka, Schildenfeld, Strinic, Vukojevic, Rakitic (Dujmovic 90), Modric, Perisic (Eduardo 89), Mandzukic, Jelavic (Kranjcar 72).
Goals: Mandzukic 3, Jelavic 43, Given 49 og.
Mario Mandzukic ripped the Republic of Ireland''s hopes of a winning start to Euro 2012 apart as Giovanni Trapattoni''s 14-game unbeaten run ended in Poznan.
The Wolfsburg striker opened the scoring with a third-minute header and then after Everton''s Nikica Jelavic had cancelled out Sean St Ledger''s 19th-minute equaliser, saw his second-half attempt come back off the post and end up in of the net after ricocheting off unfortunate keeper Shay Given.
But for all Ireland''s industry and endeavour, Slaven Bilic''s men were good value for a victory which left them top of Group C following the 1-1 draw between Spain and Italy earlier in the day.
The defeat - just the third competitive reverse during Trapattoni''s four-year tenure and the first on foreign soil - means the Republic head into Thursday night''s showdown with the Spaniards, reigning world and European champions, knowing their hopes of qualification could effectively be over if they do not come away with at least a point.
Resilience has been the keyword for the 73-year-old Italian since he accepted the challenge of trying to restore Ireland''s fortunes, but while there was no shortage of willingness for the fight, Croatia simply had too much quality, and were ruthless enough to accept the slices of good fortune which came their way.
Ireland emerged from the tunnel before kick-off to be greeted by a sea of green and a torrent of noise as they embarked upon their first game at the European Championship finals for 24 years.
But within three minutes, a sizeable proportion of the hope and expectation which has mounted since qualification via the play-offs in November last year had evaporated.
Croatia started much the better and received their reward when captain Darijo Srna''s right-wing cross clipped full-back Stephen Ward and sat up for Mandzukic.
The striker had slipped as Srna prepared to deliver, but managed to right himself and head towards the bottom corner.
His effort looked to lack power, but Given, whose fitness had been a major talking point for the previous three weeks, just could not get to the ball in time.
Bilic''s men scented victory as Mandzukic and strike-partner Jelavic repeatedly stretched Richard Dunne and St Ledger at the heart of Ireland''s defence, the signs were ominous.
Full-backs Srna and Ivan Strinic repeatedly made their way forward to occupy wingers Aiden McGeady and Damien Duff in areas of the pitch where they would rather not have been, and with Luka Modric starting to pull the strings in the middle of the field, Ireland were desperately in need of inspiration.
It arrived, firstly in the shape of striker Kevin Doyle and then St Ledger with 19 minutes gone.
The combative Doyle was giving Corluka a torrid time and forced the Tottenham defender to concede one of a series of free-kicks.
McGeady''s delivery to the far post was firm and true and with Corluka out of position, St Ledger crept in front of him to head the Republic level from close range.
The noise which erupted as the ball hit the back of the net was phenomenal and roared on by the bulk of a crowd of 39,550, Ireland started to make a game of it.
Given dispelled any fears of his health with a fine diving save from Ivan Perisic''s firmly-struck 22nd-minute shot, and he was grateful to see the same man thump a dipping volley wide nine minutes before the break.
However, Ireland looked to be heading in at the break all square until disaster struck with two minutes of the half remaining.
The increasingly influential Modric cut inside the covering Robbie Keane to fire in a long-range shot which was blocked, but in his haste to clear, Ward could only slice the loose ball to the delighted Jelavic, who easily beat Given from close range to restore his side''s advantage.
Given''s luck deserted him totally within three minutes of the restart when Mandzukic powered a header towards goal from a Perisic cross and saw the ball come back off the post, hit the keeper on the head and fly into the unguarded net.
Trapattoni made a double substitution just eight minutes into the second half when he replaced Doyle and McGeady with Jon Walters and Simon Cox, and the latter sent a long-range effort high over Stipe Pletikosa''s crossbar within seconds of his arrival.
But with Croatia by now firmly in the driving seat and knowing victory was within their grasp, the Republic found themselves struggling to make it out of their own half.
However, they were convinced they should have been awarded a 63rd-minute penalty for central defender Gordon Schildenfeld''s crude challenge from behind on Keane, although Dutch referee Bjorn Kuipers took a markedly different view.
Dunne headed a 68th-minute Duff free-kick straight at Pletikosa, but Croatia were cruising towards victory without having to expend unnecessary energy.
Midfielder Ivan Rakitic curled a 77th-minute shot inches wide and Keith Andrews power a header agonisingly past the post at the death, but the points had been secured long before.
EURO 2012
GROUP STAGES
Friday June 8
Poland 1 Greece 1
POLAND: Szczesny, Piszczek, Wasilewski, Perquis, Boenisch, Murawski, Polanski, Blaszczykowski, Obraniak, Rybus (Tyton 69), Lewandowski.
Goal: Lewandowski 17.
GREECE: Chalkias, Torosidis, Papastathopoulos, Avraam Papadopoulos (Kyriakos Papadopoulos 36), Holebas, Maniatis, Katsouranis, Karagounis, Ninis (Salpingidis 46), Gekas (Fortounis 68), Samaras.
Goal: Salpingidis 51.
Russia 4 Czech Republic 1
RUSSIA: Malafeev, Aniukov, Berezutsky, Ignashevich, Zhirkov, Shirokov, Denisov, Zyryanov, Dzagoev (Kokorin 84), Kerzhakov (Pavlyuchenko 73), Arshavin.
Goals: Dzagoev 15, Shirokov 24, Dzagoev 79, Pavlyuchenko 82.
CZECH REP: Cech, Gebre Selassie, Hubnik, Sivok, Kadlec, Plasil, Jiracek (Petrzela 75), Pilar, Rosicky, Rezek (Hubschman 46), Baros (Lafata 85).
Goal: Pilar 52.
Saturday June 9
Holland 0 Denmark 1
HOLLAND: Stekelenburg, Van Der Wiel (Kuyt 84), Heitinga, Vlaar, Willems, Van Bommel, Nigel De Jong (Van der Vaart 71), Robben, Sneijder, Afellay (Huntelaar 71), van Persie.
DENMARK: Andersen, Jacobsen, Kjaer, Agger, Simon Poulsen, Kvist Jorgensen, Zimling, Rommedahl (Mikkelsen 83), Eriksen (Schone 74), Krohn-Delhi, Bendtner.
Goal: Krohn-Delhi 24.
Germany 1 Portugal 0
GERMANY: Neuer, Boateng, Hummels, Badstuber, Lahm, Khedira, Schweinsteiger, Muller (Bender 90), Ozil (Kroos 87), Podolski, Gomez (Klose 80).
Goal: Gomez 72.
PORUGAL: Rui Patricio, Joao Pereira, Bruno Alves, Pepe, Fabio Coentrao, Meireles (Varela 80), Veloso, Joao Moutinho, Nani, Postiga (Nelson Oliveira 70), Ronaldo.
Sunday June 10
Republic of Ireland 1 Croatia 3
REP IRELAND: Given, O'Shea, St. Ledger, Dunne, Ward, McGeady (Cox 54), Whelan, Andrews, Duff, Doyle (Walters 53), Keane (Long 75).
Goal: St. Ledger 19.
CROATIA: Pletikosa, Srna, Corluka, Schildenfeld, Strinic, Vukojevic, Rakitic (Dujmovic 90), Modric, Perisic (Eduardo 89), Mandzukic, Jelavic (Kranjcar 72).
Goals: Mandzukic 3, Jelavic 43, Given 49 og.
Spain 1 Italy 1
SPAIN: Casillas, Arbeloa, Pique, Sergio Ramos, Jordi Alba, Xavi, Busquets, Alonso, Silva (Jesus Navas 65), Fabregas (Torres 74), Iniesta.
Goal: Fabregas 64.
ITALY: Buffon, Chiellini, De Rossi, Bonucci, Giaccherni, Marchisio, Pirlo, Thiago Motta (Nocerino 89), Maggio, Cassano (Giovinco 65), Balotelli (Di Natale 56).
Goal: Di Natale 60.
Monday June 11
Donetsk, Group D: France v England (1700)
Kiev, Group D: Ukraine v Sweden (1945)
Tuesday June 12
Wroclaw, Group A: Greece v Czech Republic (1700)
Warsaw, Group A: Poland v Russia (1945)
Wednesday June 13
Lviv, Group B: Denmark v Portugal (1700)
Kharkiv, Group B: Holland v Germany (1945)
Thursday June 14
Poznan, Group C: Italy v Croatia (1700)
Gdansk, Group C: Spain v Republic of Ireland (1945)
Friday June 15
Donetsk, Group D: Ukraine v France (1700)
Kiev, Group D: Sweden v England (1945)
Saturday June 16
Wroclaw, Group A: Czech Republic v Poland (1945)
Warsaw, Group A: Greece v Russia (1945)
Sunday June 17
Kharkiv, Group B: Portugal v Holland (1945)
Lviv, Group B: Denmark v Germany (1945)
Monday June 18
Gdansk, Group C: Croatia v Spain (1945)
Poznan, Group C: Italy v Republic of Ireland (1945)
Tuesday June 19
Donetsk, Group D: England v Ukraine (1945)
Kiev, Group D: Sweden v France (1945)
QUARTER-FINALS
Thursday June 21
Warsaw, QF1: Winner A v Runner-up B (1945)
Friday June 22
Gdansk, QF2: Winner B v Runner-up A (1945)
Saturday June 23
Donetsk, QF3: Winner C v Runner-up D (1945)
Sunday June 24
Kiev, QF4: Winner D v Runner-up C (1945)
SEMI-FINALS
Wednesday June 27
Donetsk, SF1: Winner QF1 v Winner QF3 (1945)
Thursday June 28
Warsaw, SF2: Winner QF2 v Winner QF4 (1945)
FINAL
Sunday July 1
Kiev: Winner SF1 v Winner SF2 (1945)