Germany 3-0 Slovakia: Joachim Low and Jan Kozak reaction

Germany still have plenty of room for improvement after easing into the Euro 2016 quarter-finals by beating Slovakia 3-0 on Sunday, coach Joachim Low warned.

The reigning world champions were comfortable winners in their last-16 clash in Lille as Jerome Boateng, Mario Gomez and the excellent Julian Draxler all scored while Mesut Ozil had an early penalty saved.

"We put in a great effort, both defensively and going forward, but with all due respect to our opponents we cannot say from this that we are going to dominate the competition. We will have to improve to win the tournament," said Low.

Germany 3-0 Slovakia

Germany 3-0 Slovakia: Julian Draxler seals Euro 2016 quarter-final spot

Germany will face either reigning European champions Spain or old rivals Italy in Bordeaux in the last eight next weekend but Low said he is not worried about who his side meet next.

"I am sleeping well," he continued. "Both teams are among the favourites. Italy are incredibly strong defensively while Spain are the best attacking side we have seen in recent years.

"We have to improve if we want to compete with the other teams to win the title. Our task now will be more difficult and we cannot leave our opponents any spaces because teams will punish us. We also have to take our chances in the games we have coming up."

The main source of satisfaction so far for Low has been in defence with Germany having reached the last eight without conceding a goal in any of their four matches at the tournament.

"I am happy the defence has performed so well so far but now we will come up against much more dangerous sides who have top strikers," Low added before heaping praise on Boateng, whose goal was his first for his country on the occasion of his 63rd cap.

"There is no need to say anything more about his value to us. That has been clear for years now," he said.

"The defence was excellent today. Boateng and [Mats] Hummels won almost every challenge, they were focused, they helped build the play and then Boateng scored the goal."

Slovakia coach Jan Kozak lamented the performance of his side, saying: "I think several of our players didn't play to their best and when you have two or three players who are not really focused on the game and don't follow your instructions it's difficult to get anything from the game.

"Germany perhaps started slowly in the group stage but they are a tournament team and they know when to play really well. It was a great collective performance from them.

"Obviously any defeat is painful regardless of the opposition but I think there's a good feeling that we made the last 16 and played the world champions.

"In one month we have played them twice, won one and lost one, so that's quite good."