Croatia pair clicking right away

It is, Nikica Jelavić assures us, "a feeling you cannot explain in simple words", but, as the Croatia striker replays in his mind the instance he put the ball past Shay Given on Sunday, he tries all the same. "At that moment you feel so many emotions that you could not believe," he tells UEFA.com. "You just yell and you're so crazily happy. It's incredible."

It is strange to think that Jelavić had not struck a competitive international goal before Croatia's victory over the Republic of Ireland; baffling, in particular, for anyone who has seen his free-scoring exploits for Everton FC following his January transfer from Rangers FC.

The 26-year-old arrived at UEFA EURO 2012 on the back of a run of ten goals in as many games for the Merseyside club and his confident finish when the ball broke to him two minutes before half-time in Poznan recalled an impressive run of first-time strikes in Everton blue.

Jelavić, who started just three games in qualifying, acknowledges that his Premier League feats have left his confidence sky-high. "In those five months at Everton in the second half of the season, I played fantastic, and I'm very satisfied. I didn't dare hope it would be that good after signing, but it helped me a lot," he says.

Croatia coach Slaven Bilić, himself once an Evertonian, will have been well aware of the potential impact an in-form Jelavić would make here in Poland, but what he could not have known was just how well he would click with fellow striker Mario Mandžukić.

The pair had barely played together before Sunday's opening Group C match but their fledgling partnership could not have been more fruitful given it was Mandžukić who headed Croatia's two other goals – the second with the help of a kind deflection off a post and Ireland goalkeeper Given.

Bilić, not surprisingly, was delighted with what he saw from the pair, telling UEFA.com: "They are two forwards who are good off the pitch, they are great friends, they understand each other and support each other, and they are difficult to mark because they are good on the ground and in the air."

Suddenly the pre-tournament loss of Ivica Olić feels less significant to Croatia, who can also call on Eduardo and Nikola Kalinić. "They were on the bench this time, but they are players who can give a lot to the national team," Jelavić reminds us. What Mandzukić offers, he adds, is plenty. "Mandzukic is a fantastic player. He runs a lot, it looks like he never gets tired, he scores goals, and that is the kind of player we need right now."

Mandžukić, who scored 12 Bundesliga goals for VfL Wolfsburg in 2011/12, is just as positive about their partnership. "Jela and I haven't played together many times before, so we needed some time to get in tune with each other and now we've shown that we fit in well alongside each other, along with the rest of the team." The pair worked closely together at Croatia's pre-tournament training camp and could be seen offering each other words of encouragement during Sunday's game – as well as sharing a special handshake as the goals flew in.

Like Jelavić, Mandžukić is playing at his first major tournament. Unlike him, he scored three times in ten qualifying appearances, though his double against the Irish was still something to treasure – only Davor Šuker previously had scored twice in a EURO match in Croatia's checkerboard shirts. "Of course it means something to me," he tells UEFA.com. "We all know who Davor Šuker was – he was a great attacker, a great player." Little wonder he was on the phone home to his parents straight after the match.

Once, that is, he had left a happy, noisy dressing room. "A few days before the game we were under a lot of pressure, our country expected a lot from us and we were aware of this," he explains. When the final whistle blew, "we knew that we had done something magnificent".

It is just the beginning, though, for a team who must still take on Italy and Spain, starting with the Azzurri in Poznan on Thursday. Jelavić was impressed by Italy – "a very experienced tournament team" – in their opening draw with Spain and knows a tough assignment awaits.

"We need to prepare well, analyse them, find their weaknesses, where and how to attack them," he says. "Of course the best thing for us would be to win, to be safe and through to the second round after the second group game. But against Spain they played great, even better than Spain. We expect a difficult game." On Sunday's evidence, Italy's defenders will be thinking just the same.