World champions Germany led a group of five teams through to the last 16 of Euro 2016 on Wednesday after Mario Gomez struck the only goal in a 1-0 victory over Northern Ireland.

Gomez's 30th-minute effort in Paris ensured Germany advanced as winners of Group C, with Poland through as runners-up following a 1-0 win over Ukraine.

Wednesday's results also mean that Croatia, Slovakia and Hungary are all guaranteed to reach the knockout stages.

Gomez was thrust into Germany's starting XI after Joachim Loew's side laboured to a 0-0 draw against Poland last week. The on-loan Besiktas striker repaid his coach's faith with the only goal at the Parc des Princes.

Germany dominated, with Thomas Mueller, who set up Gomez's goal, twice firing against the woodwork in the first half. Northern Ireland goalkeeper Michael McGovern pulled off several saves to limit the damage.

Germany will now play the third-placed team in Group A, B or F in Lille on Sunday.

"We played well and we were convincing but we didn't score nearly enough. That was really lacking today" said defender Mats Hummels.

"When we play against the really top teams we'll have to give it that little bit more."

Coach Joachim Loew also bemoaned missed opportunities. "We created some very good chances, but also squandered a few.

"They had no chances, but we needed to have had more purpose and consistency in front of goal. It was good in terms of the football we played, but we should have been more dominant," Loew said.

Despite the loss, McGovern's heroics could still prove vital as the Northern Irish wait to see if they qualify as one of four best third-place teams.

Half-time substitute Jakub Blaszczykowski needed just nine minutes to fire Poland past the Ukraine in Marseille.

Blaszczykowski swept home a tidy finish following a cleverly-worked corner to leave Poland on seven points, level with Germany, but behind their neighbours on goal difference.

"We would have liked to have scored more goals, but when you see in the standings that we're only separated by goal difference from world champions Germany, you have to be happy," said goalkeeper Lukasz Fabianski.

"It's the first time in 30 years we've qualified from the group stage, we know we can go further and play better."

For Ukraine it was a third successive loss and the last match for coach Mykhaylo Fomenko, who announced earlier on Tuesday that he would leave his post following the tournament.

Spain are already assured of reaching the next round as they seek a third consecutive European crown, but Vicente Del Bosque's side want to clinch top spot in Group D when they face second-placed Croatia in Bordeaux later.

Croatia suffered a huge blow when Real Madrid star Luka Modric was ruled out by injury.

Czech Republic could poach the other automatic qualifying berth should they beat Turkey and Croatia lose. But coming second, instead of third, in that group could prove a poisoned chalice.

With Italy guaranteed to finish top of Group E, whoever finishes second in Group D will likely have to get past the Euro 2012 finalists and then Germany to reach the semi-finals.

Hosts France or England could then stand in the way of a place in the July 10 final.