Fernando Torres scored twice on his return to the starting lineup as stylish Spain thrashed Ireland 4-0 on Thursday to go top of Group C with Croatia and end Irish hopes at Euro 2012.
Croatia had earlier come back to earn a 1-1 draw with Italy which left the Italians in danger of an early exit after Mario Mandzukic's 72nd minute strike cancelled out Andrea Pirlo's curling free-kick from 25 meters in the 39th.
Torres smashed the ball past keeper Shay Given in the fourth minute and confidently struck his second on the break in the 70th, justifying his inclusion instead of Cesc Fabregas after the title holders' toothless 1-1 draw with Italy on Sunday.
David Silva had added the second for the world and European champions by calmly placing the ball wide of a cluster of defenders in the 49th minute, and Fabregas scored the fourth in the 83rd after coming off the bench.
Spain and Croatia lead the group on four points, with Italy down but not out on two, and Ireland no longer in contention following their 3-1 defeat by the Croats on Sunday.
The headlines off the pitch were stolen by the repercussions of clashes between Russian and Polish supporters before their teams drew 1-1 in a Group A match in Warsaw on Tuesday.
Poland's president and sports minister called for tougher punishment after the first people received what he considered light sentences over the violence in which 184 people were detained, most of them Poles.
Poland, co-hosting the tournament with Ukraine, expects 20,000 Russian fans to arrive in Warsaw with tickets for their team's final group match against Greece on Saturday, twice the number that came to the game with Poland.
Russia has demanded Poland protect its fans and says it will appeal against a decision by UEFA to dock its team six points in qualifying for the next European Championship if their fans misbehave again after crowd trouble at an earlier match.
Torres quickly made an impact on his recall to the Spanish side when he was quickest to a loose ball after defender Richard Dunne tackled Silva. He rounded Stephen Ward and hit an angled shot high into the net past the helpless Given.
It was his first tournament goal since scoring the winner against Germany in the Euro 2008 final.
Silva got the second when Given parried an Andres Iniesta shot into his path, and then played Torres clean through for him to slot his 30th international goal into the bottom right corner. He is now Spain's third highest all-time scorer.
Fabregas fired Spain's fourth goal in off a post from a tight angle nine minutes after replacing Torres, whose name was chanted by the Spanish fans as the final whistle neared.
Mandzukic was again the hero for Croatia as he scored his third goal of the tournament after his headed brace against Ireland. He slammed the ball in from close range after bringing down an Ivan Strinic cross that Giorgio Chiellini misjudged.
Pirlo's goal had made him the first player to score directly from a free kick at the European Championship since 2004, but it was the Italians' only reward for a first half they dominated.
Italy coach Cesare Prandelli said his team should have wrapped the match up early on.
"We had some good chances in the first half and could have done better. We missed a bit of energy and grit," he said.
Mario Balotelli was one of the culprits as Italy wasted several chances and were frustrated by goalkeeper Stipe Pletikosa, who made a brilliant double save at the feet of Claudio Marchisio.
"We weren't good enough in the first half but we regrouped at halftime and in the second half we dominated and got a deserved equalizer," Croatia defender Vedran Corluka said.
Croatia, however, could be in trouble after their fans threw flares onto the field, at one point leaving a pall of smoke hanging over the penalty area.
RUSSIA TO APPEAL
Russia said they would do all they could to head off any punishment over their Group A match against the Czech Republic in Wroclaw last Friday after Russian fans set off and threw fireworks and displayed illicit banners during the 4-1 triumph.
UEFA, European soccer's governing body, also meted out punishment to the German and Portuguese football associations over incidents during a Group B match on Saturday.
The German federation was fined 10,000 euros ($12,600) after Germany fans threw what appeared to be rolled up pieces of paper at Portugal players on several occasions during the first half.
The Portuguese association was fined 5,000 euros for delaying the start of the second half in Lviv.
(Editing by Ed Osmond and Ken Ferris)