By JACKSON MILLER 

The first four rounds of the AFL have been filled with upsets, making for an interesting and unpredictable season. Add to that, some unexpected injuries and illnesses.

As the fifth round progresses, let’s take a look at the top 5 surprises so far:

#1 Reigning premiers lose to “bottom four” Lions

One of the biggest upsets happened in one of the first games of the season. Most footy experts would have considered West Coast almost a certainty to beat Brisbane, especially considering that the Lions not only didn't make the finals, but finished in the bottom four.

For the Eagles to lose in the opening round, especially to the Lions by 44 points, was not something anyone saw coming.

Brisbane continued to dominate until Round 4 when they lost to Essendon by 47 points.

#2 Chris Mayne injured in landmark game

Collingwood supporters were left disappointed when Chris Mayne’s 200th game was cut short by injury.

Mayne was tackled five minutes into the first quarter of the Round 4 match against the Bulldogs. He was limping afterward with a suspected corked thigh.

A video of the clash revealed that he had taken a knee in the back from Mitch Wallis, and was taken to hospital, unable to join in the team’s post-match celebration of their 14-point win.

Scans confirmed that the wingman had suffered a small fracture to his lower back, and he is now expected to miss four to six weeks.

#3 Geelong’s winning streak comes to an end

Geelong’s winning streak came to an end in Round 4 when they faced Greater Western Sydney at home.

The Cats dominated the first half, creating eight of the first nine forward 50 entries and firing the first five scoring shots for a return of 2.3 (15) to nil after 15 minutes. They led by 21 points early in the second quarter before the Giants finally found their mojo.

Despite being a man down, GWS bounced back in the second quarter and narrowed the lead to eight points.

This led to more action from Geelong, who extended it back to 22 points after the half-time break. After this, it was nothing but back-and-forth action, with the Giants eventually clawing a four-point victory.

#4 Dayne Beams left out of Bulldogs game due to illness

The loss of champion wingman Chris Mayne to injury wasn’t the only surprise during last Friday’s Collingwood-Bulldogs clash.

Dayne Beams was taken out right before the game because of an illness, described as a migraine.

Father-son recruit Callum Brown was his replacement. Beams has since said he suffered both a virus and a migraine during that week.

#5 An upside-down ladder

A massive surprise this season has been the fact that outsiders have surpassed the favourites.

Teams that most experts gave only an outside chance have walked away with the most wins. These results have created an almost upside-down ladder compared to what many predicted.

At the end of round 4, six sides were at 3-1, including Brisbane, Gold Coast and St Kilda – all in the bottom four at the end of last season.