"Last season was Harry's best for Liverpool and it was very unfortunate he was hurt in the cup final," said the Reds boss.
"He had a very good year and I'm sure he can play as well for Australia in the World Cup. He will be one of their most important players because he has the ability to win games, create goals and score.
"He'd had no problems with his fitness since his comeback and he was getting stronger with every game. The last injury wasn't the same and I'm pleased it's not proving to be a big problem.
"There were a lot of games last season when we saw Harry beating players and making a lot of crosses. He played his part in a much better season for us in the Premiership.
"Like all of the Liverpool players in Germany, he should go to the World Cup feeling very confident in his ability."