Chile surprised many people by knocking out defending champions Spain and qualifying for the Round of 16 with a game to spare. How far do you think they can go in this World Cup?
Hamann: This wasn't a shock result for me. I rate Chile very highly.
After this performance, I absolutely believe they are contenders to win the tournament.
I rate them higher than even Holland.
There are three teams whom I rate as favourites: Argentina, Germany and Chile.
We know, of course, what Germany are capable of. Argentina didn't play well in their first game against Bosnia and Herzegovina, but maybe the pressure of the opening game got to them.
Unlike Brazil, Argentina still have room for improvement. But Chile are really a very good side. In the run-up to the World Cup, they beat England 2-0 comfortably in a friendly at Wembley.
They even played Germany off the park in another friendly, even though they lost that match 1-0 in Stuttgart.
Going forward, they have two excellent players in Alexis Sanchez and Arturo Vidal.
The whole team have energy and stamina, and they recover the ball quickly. With these qualities, they have a chance to beat any team.
What do you think went wrong for Spain in this tournament?
Hamann: The biggest mistake Spain coach Vicente del Bosque made was to play Diego Costa as striker.
He has been disappointing. His style of play simply doesn't suit this team. He's direct and physical, the sort of player you use to come off the bench to chase a game and rough up defenders.
Goalkeeper Iker Casillas has come under plenty of criticism too, and rightly so because he made two or three big mistakes. But you couldn't have foreseen that happening, especially since he had just won the Champions League with Real Madrid last month.
But to play Costa was the biggest mistake. This team could have done so much better if they had played without strikers, as they had done in the past by using Pedro Rodriguez or Cesc Fabregas as a false No. 9.