Sergio Busquets believes Spain are growing stronger by the game at Euro 2020 after La Roja defeated Croatia 5-3 in a European Championship classic to reach the quarter-finals.

Luis Enrique's side won their first knockout game at a major tournament since winning Euro 2012 nine years ago, triumphing in a thrilling contest at Parken Stadium on Monday.

Pablo Sarabia, Cesar Azpilicueta and Ferran Torres were all on target to give Spain a commanding 3-1 lead after Pedri's bizarre own goal from 49 yards had put Croatia ahead.

But substitute Mislav Orsic scored one and set up another for Mario Pasalic in the space of seven minutes late on in Copenhagen to set up extra time.

It is the just the second time Spain have conceded three goals in their Euros history, but they won the match through extra-time strikes from Alvaro Morata and Mikel Oyarzabal, both goals set up by substitute Dani Olmo.

Spain captain Busquets was particularly pleased with the way his side responded to the own goal, with Unai Simon miscontrolling Pedri's backpass and letting the ball roll into his own net.

"Unai knows he's got our total confidence. The goal was bad luck but his mentality is very laidback while remaining ambitious, and he showed that today," Busquets said after collecting the man of the match award at full-time.

"He was ultra-secure after the goal and made some top saves. The team has managed to recover and it is a great victory. This win leaves us good feelings. The team knows what it plays and what it wants. 

"We are a difficult opponent to beat and are growing stronger in this tournament as it goes."

Spain are the first side in European Championship history to score five or more goals in successive games, with five different players registering for La Roja in a single game at a major tournament for the first time.

However, Busquets admits there is room for improvement after giving away a comical opening goal and allowing Croatia a way back into the game when in control with five minutes left.

"We had chances to finish the game off quite early on but we showed character throughout," he said. "When Croatia changed their system, they flooded the pitch high up and we didn't adjust quickly enough.

"Scoring five times and going through still suggests that we have to improve, but to get to the quarter-finals is an indication that we're a good team. 

"We were very good today, very intense, well prepared and we beat a very, very difficult rival here."

Monday's match was the second-highest scoring contest in European Championship history, behind only France against Yugoslavia in the 1960 semi-finals (a 5-4 victory for Yugoslavia).

Croatia ultimately came out the wrong side of the eight-goal classic, and captain Luka Modric accepts his side lacked the quality needed to complete a famous comeback.

"We took the lead from a lucky goal. Afterwards, they were better – at least for the first 60 minutes," he told HRT. "We stood too deep in our half and let them play. 

"When we attacked more, we played better and created more chances and that is where the equaliser came from; when we showed quality and character. 

"At the start of extra time we had them on the ropes but we failed to score from two good chances. Then the game turned around and we didn't have the strength to come back."