Croatia will need to keep possession as much as possible to unsettle Spain in its Euro 2020 last-16 clash in Copenhagen on Monday if it is to advance to the quarter-final, goalkeeper Dominik Livakovic said.

Croatia reached the knockouts with a 3-1 Group D win over Scotland on Tuesday to set up a clash with Spain, which progressed from Group E thanks to a 5-0 drubbing of Slovakia.

The win over Scotland boosted Croatia's confidence after poor performances in a 1-0 defeat by England and a 1-1 draw with the Czech Republic, but Livakovic said this team must now forget about the ups and downs of the group stage.

"The knockout stage is like a new tournament altogether and although Spain are an outstanding team full of top quality players, I am sure they will be wary of us too," Livakovic told a news conference from Croatia's Rovinj base camp on Thursday.

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"We need to keep possession as much as possible and make them anxious because they don't like playing against teams who can do that. It's going be tough but at this stage only the best teams are still in the tournament.

"From here on you have to win every game to become the European champions."

The Croatians beat Spain 3-2 at home in the 2018-2019 Nations League after being hammered 6-0 in the reverse fixture, while they also prevailed 2-1 in the group stage at Euro 2016.

Coach Zlatko Dalic was not thrilled to learn that Croatia would face Spain and not Sweden, which clinched top spot in Group E thanks to a stoppage-time goal in a 3-2 win over Poland.

"We're up against one of the strongest teams left in the tournament who are pacy and full of energy, having showed their class against Slovakia," said Dalic.

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"It will be a high-octane clash and a real challenge but we showed in the second of those two Nations League meetings that we can stand our ground against them.

"We’ll have to take the game to them and respond to their relentless pressing if we are to advance to the quarter-finals. Having our fans in numbers for the clash in Copenhagen will be a big bonus."

The winners will take on either world champion France or Switzerland in the quarter-final.