Brazil striker Leonardo got his first start of the FIFA U-17 World Championship in Dunedin on Sunday and repaid his coach's faith with a hat trick to put the defending champions through to the semifinals.

Brazil doubled their tally of goals for the tournament in beating Paraguay 4-1 in their quarter-final tie at Carisbrook and set up a semifinal meeting with Ghana in Auckland.

Earlier, Australia reached the semifinal of a FIFA U-17 World Championship event for the first time by beating Qatar in Christchurch with a sweet second-half strike from substitute Joseph Di Iorio.

The German-based forward hit a left-footed volley from outside the penalty area to ensure a meeting with the USA on Wednesday in their semifinal.

Brazil, who had scored just twice in their three first round games, came good against a timid Paraguay, with Leonardo scoring all three of his goals by clever positioning at the far post.

Paraguay were still in the game at half-time after Alejandro da Silva had scored in the 42nd minute to make the score 2-1, but Leonardo stretched the lead by completing his hattrick 10 minutes after the interval and then Caca got a last-minute goal to emphasise the defending champions' dominance.

Brazil's next meeting with Ghana is a repeat of the last FIFA U-17 World Championship final in Egypt, where the South Americans triumphed.