Karim Benzema struck a hat-trick as Real Madrid thrashed arch-rivals and league leaders Barcelona 4-0 to reach the Copa del Rey final in stunning fashion on Wednesday.

Barca, bidding for a fourth successive Clasico victory this season, looked set for the final having edged a 1-0 win in the first leg of the semi-final in Madrid last month, reports Reuters.

But after dominating the early stages of the second leg they fell apart in unlikely fashion to lose 4-1 on aggregate with Benzema becoming the first Real player to score a hat-trick in a Clasico at the Nou Camp since Ferenc Puskas in 1963.

Vinicius Jr gave Real the lead in first-half stoppage time following a lightning counter-attack and the semi-final was turned on its head when Benzema stroked a shot into the corner five minutes into the second half from a Luka Modric pass.

Eight minutes later Vinicius was fouled in the area and Benzema thumped his penalty past Marc-Andre ter Stegen.

With jeers echoing around the Nou Camp, Barcelona tried to respond but it was Real Madrid who looked the more likely to add to their tally with Benzema unstoppable.

In the 80th minute he was again set up by Vinicius to complete his second hat-trick in a matter of days having also hit a treble in the 6-0 destruction of Real Valladolid.

Real will fancy their chances of winning the trophy for a 20th time when they face Osasuna in the final after they beat Athletic Bilbao 2-1 on aggregate on Tuesday.

"It was a complete match. If you don't make it complete, you can't win 0-4 here," Ancelotti said.

"In the first half we had difficulties but the first goal changes the dynamics of the whole match.

"It's a game in which personality and experience is a very important aspect. We mixed the energy of Rodrygo, Valverde and Camavinga with the experience of Vini, Modric, Kroos. They played a spectacular game."

After suffering at the hands of Barcelona this season, it was a spectacular riposte by Ancelotti's side as Real beat Barca by at least a four-goal margin for the first time since 1995.

Real are a distant second behind Barca in La Liga having lost 2-1 to their bitter rival last month. But while the title may be gone, they regained bragging rights in style.

There was no hint of what was to come on Wednesday as Barcelona looked in the mood to kill the tie with Thibaut Courtois thwarting the hosts on a number of occasions.

It was from one Courtois save to deny Robert Lewandowski that the tie turned in an instant.

Real broke forward at pace and Vinicius exchanged passes with Benzema before his shot crept over the line despite the efforts of defender Ronald Araujo to keep it out.

Five minutes after the break Modric glided in from the right and rolled a pass to Benzema to send a precise finish into the corner. Xavi's Barcelona were in tatters minutes later when Vinicius was fouled and Benzema exacted punishment.

Tempers flared with players from both sides getting involved in skirmishes but Benzema had the last laugh to complete a magical night for Real and one Barca will want to forget.

"Congratulations to Real Madrid, who had a great second half," Barca coach Xavi, who was booked in the first half, said. "If you show Madrid mercy, they don't show you mercy.

"It will be hard to sleep, as I am from Barcelona and many of the squad are. But tomorrow, we think about Girona."