The winners of the past two World Cups brought different styles into the Group C opener at Gdansk, Poland, but matched each other, trading goals in the second half.
Italy's three-man defense soaked up Spanish passing moves before taking the lead through substitute Antonio Di Natale in the 61st minute.
Spain started without a traditional center forward, using Cesc Fabregas as the attacking spearhead, and the Barcelona midfielder equalized in the 64th.
Spain vs. Italy is always billed as a heavyweight bout and the teams did not disappoint.
Spain's short-passing specialists swarmed over the Italian half of the field early on without worrying goalkeeper Gianluigi Buffon.
The Italian breakthrough came when majestic midfielder Andrea Pirlo released Di Natale, who had replaced Mario Balotelli minutes earlier.
The 34-year-old forward calmly slipped his shot past Spain keeper Iker Casillas, captaining his country as did Buffon.
Fabregas leveled when he met David Silva's perfectly angled pass with a first-time shot. Spain coach Vicente del Bosque chased a win by sending on a more traditional striker, Fernando Torres, to replace Fabregas. But Torres repeated his lackluster form for Chelsea when wasting two late chances.
The draw ended a 14-match winning streak for Spain in competitive matches, which began after a 1-0 loss to Switzerland to open the 2010 World Cup.
The later match in Poznan failed to scale such heights of technical play. Ireland's large contingent of traveling fans waited 10 years to return to a tournament finals, and saw their team trail within three minutes.
Mario Mandzukic scored with a header, and added another in the 48th. Forward Nikica Jelavic seized on a misdirected Irish clearance to score in the 43rd.
Ireland got its goal from defender Sean St. Ledger's header in the 19th.
UEFA promised zero tolerance for breaking rules at Euro 2012 and now has acted against three of the 16 competing nations. Croatia likely will follow after a firework was thrown on the field from a section containing its fans, and delayed the restart after Jelavic's goal.
Germany fans threw crumpled paper balls at Portugal players during a 1-0 victory Saturday in Lviv. Ukraine.
“The German Football Association (DFB) is charged with the throwing of missiles by its supporters,” UEFA said in a statement. “The Portuguese Football Federation (FPF) faces proceedings for a delayed kickoff to the second half.”
Both teams face financial penalties when UEFA reviews the cases Thursday.
The Russian Football Federation warned fans that hooliganism could cost the team points on Wednesday when UEFA hears its case.
Video emerged on Saturday of Russia fans attacking stadium stewards in Wroclaw after beating the Czech Republic 4-1 victory on Friday. The Football Union of Russia called on its traveling fans to “Respect yourself, your home and your team.”
Federation President Sergei Fursenko and team coach Dick Advocaat, who is Dutch, joined a monthly vigil honoring late Poland President Lech Kaczynski. The symbolic gesture came amid ongoing tensions between Poland and Russia based on a difficult history of war and occupation, and the aftermath of the plane crash.
UEFA is also investigating reports by anti-racism monitors of abuse directed by Russian fans at Czech defender Theodor Gebre Selassie, who is black.
Selassie told The Associated Press on Sunday that he noticed the insults aimed at him.
“It was nothing extreme. I've experienced much worse,” said the 25-year-old defender, whose father is Ethiopian.
Sunday's results at a glance
Spain 1, Italy 1
Croatia 3, N. Ireland 1