Ghana substitute Jordan Ayew grabbed a hat-trick to stake his claim for a starting place in a convincing 4-0 win over a sloppy South Korea side in their final World Cup warm-up on Monday.

World Cup quarter-finalists in 2010, Ghana scored twice in the first half through Ayew and Asamoah Gyan before the former grabbed two more in the second half for the Black Stars.

Kwesi Appiah's Ghana are in one of the toughest groups in Brazil with a 16 June opener against the United States before they play European powerhouses Germany and Portugal in Group G.

"I don't look at the scoreline but how we played individually and as a team," said Ghana coach Appiah.

"We took our chances. Korea attacked well, but you have to be cautious at the back.

"If my team had lost by four goals it would maybe help me to look at the mistakes and correct them before the World Cup."

Ghana lost forward Majeed Waris with a thigh injury in the fourth minute after a fierce challenge by Ki Sung Yueng, who was booked, allowing the 22-year-old Ayew to come up from the bench.

The substitute did not take long to make an impact, as he gave Ghana the lead in the 11th minute with a deflected right-foot shot that looped over goalkeeper Jung Sung-ryong off Ki.

Ayew's older brother Andre had set up the chance by feeding him the ball on the edge of the area at the Miami Dolphins' Sun Life Stadium, which was filled with only a few thousand fans.

South Korea came close to an equaliser when Son Heung-Min hit the post 10 minutes before half-time, a missed chance the Koreans would rue, as Ghana soon got a second goal through the lively Asamoah Gyan, who tucked the ball past Jung after robbing Kwak Tae-hwi in midfield.

Gyan ran at the Korea defence, and although Kim Young-gwon tried to get across to cover he was too late to stop the striker firing the ball into the bottom corner of the net.

Jordan Ayew then grabbed his second of the night with a right-foot shot into the bottom left of the goal with the sleeping Korean defence again raising concerns for coach Hong Myung-bo.

Ayew, who is the son of former African Footballer of the Year Abedi Pele, saved the best for last when he ghosted into the area to expertly turn the ball home from close range.