Smolarek found space in the box to head home a Maciej Zurawski corner in the 54th minute after an otherwise dominant Croatia had struggled to create clear openings against a defensive Polish formation in the first half.

Following Saturday's loss to Columbia, Polish coach Pawel Janas dropped one striker in favour of a second holding player in a five-man midfield, with Smolarek and winger Jacek Krzynowek pushing up on the flanks.

The Croatians' best chance fell to midfielder Dario Srna, who hit the crossbar with a 30-metre free-kick in 42 minutes. Ivan Bosnjak also pushed a shot just wide of Polish keeper Artur Boruc's post after being put clean through just after the break.

"For us this was a very important game and it's good we won," assistant coach Maciej Skorza told Polish public TV, adding that Boruc was now almost certain to start in goal at the finals ahead of rival Tomasz Kuszczak.

Asked if the Poles would play the same formation in the team's Group A game against Germany, he added: "For the time being we're not going to say. It is a more defensive variant. We'll calmly analyse things and see how it all comes out."

Poland also face Ecuador and Costa Rica in Group A. Croatia open their finals campaign against defending champions Brazil in Group F, where they also face Australia and Japan.