The huge upset on Wednesday night was a sharp wake-up call for the Australians, but it must be a great occasion to celebrate for the beleaguered Zimbabwean team, as well as their supporters.
Their country has been facing hard times, and it's wonderful that their team has given them a reason to smile, by beating the world champions.
For the Australians, it was a reminder that they have to put their World Cup glory behind them, and concentrate on the tournament. I always believe that if a team has to lose in a tournament, it's better to lose early on, so I don't think the Aussies are out of it just yet.
However, their top order needs to fire in the next game if they want to get to the next round. They still have injury concerns and that would be a worry.
The Australians have been slow starters (take their loss to Bangladesh at the start of the 2005 Ashes tour, for example), but they have the ability to turn it on when it matters most, and this is why they have been so consistent in big tournaments. They also have the most number of match winners in their side, and if just one or two of them fire in every game, they will be hard to beat.
All this makes their Friday game against England even more edgy than the usual Australia-England encounter. England have the most experience in this format, and they will be backing themselves.
Add to this the fact that they have players like Kevin Pietersen and Andrew Flintoff who can turn a game around in a few overs. Many of their youngsters like Jamie Anderson, Stuart Broad and Owais Shah are coming to South Africa after a successful summer, so there will not be any lack of confidence.
In India, however, all eyes will be trained on the India-Pakistan game on Friday. Neither side has played much Twenty20, and will be a little uncertain when they take each other on.
Mahendra Singh Dhoni, India's new captain, has a great record against Pakistan, and could be a crucial factor in the game. Now that he has been entrusted with leadership, it will be interesting to see how he shapes up.
It must be remembered that India's Test and one-day captain Rahul Dravid has just won a Test series in England, and has been doing a great job at the helm. Dravid is going to be around for some more time, and there is a need to view Dhoni's performance accordingly.
If he does well it will be a good sign for the future, and everyone will be watching to see how he handles pressure, how the team reacts to his leadership and whether his batting and keeping are affected by the additional responsibility.
The Pakistan team is also in a similar position with a new captain and some inexperienced players. However, I expect players like Shahid Afridi to make crucial contributions in this tournament.
He was good with the ball against Scotland, but I expect him to explode with the bat at some stage.
Both India and England have been have been playing a lot of cricket.
However, I doubt whether the fatigue factor will come in. These are short games that last barely three hours, and can't be too taxing physically.
More importantly, this is a World Cup, and the thrill of being involved in a tournament like this is enough to lift the teams. The steady, continuous stream of games they have played recently could in fact ensure that both India and England have an edge over their opponents.