This French election race has been like no other.

Firstly the incumbent president François Hollande made history by becoming the first president deciding not to run for a second term, due to how unpopular he was.

Then both primaries for the mainstream parties threw up surprise winners.

François Fillon came from seemingly nowhere in the Republicans contest to see off both Alain Juppé, the man everyone at one time had considered a shoo-in for the top job, and former president Nicolas Sarkozy.

Then over on the left former PM Manuel Valls was handsomely beaten by rank outsider Benoit Hamon.

Then there’s been the rise and rise of independent former Economy Minister Emmanuel Macron. When he launched his movement En Marche last April, no one could have imagined that one year later he would be a frontrunner to be the next president of France

His emergence has raised the specter – that has always been considered unthinkable in France – of neither the traditional left or right making it to the second round run-off vote on May 7^th.

Then there’s Marine Le Pen who has been seemingly guaranteed a place in the second round for two years now. 

So what surprise or even surprises are left in the bag?

1. Fillon defies the odds again and becomes president

This is the obvious one.

And to be honest, even though Fillon trails Macron by between five and seven points in the polls, we shouldn’t be too surprised if he ends up being the next French president.

We might have thought the fake jobs scandal, the deluxe free suits, or his harsh economic programme to turn around France (which is off-putting for many in the centre right), would have finished off Fillon for good.

Fillon was still behind in the latest polls before the end of campaigning, but he has seen a slight resurgence in recent weeks and was considered to have a good chance of making the run-off vote. 

There are reasons why Fillon is confident he can still pass Macron and then see off Le Pen in the second round and get the keys to the Elysée.

The biggest hope for Fillon is the tens of thousands of voters who are either undecided or those who might say they will vote for Macron now, but when they get to the small polling booth they opt for Fillon.

“Better the devil you know,” was how Edouard Lecerf from polling agency Kantar Public summed up the potential mindset of voters when they get to the polling booth on April 23rd.

Ifop Pollster Jerome Fourquet said Fillon could benefit from an “army of reserves who will reveal themselves at the last minute”.

In other words how many French right wing voters out there have been saying to themselves that they will vote for Macron, or perhaps Le Pen or another candidate, but on Sunday in the privacy of the voting booth will put Fillon’s name in the ballot box?

Fillon must hope Macron's voters are as unfaithful as polls suggest.

There’s no doubt he is up against it. But then he was up against it in the primary and managed to pull off a stunning victory.

2. Macron crumbles at the finish line

Obviously an unlikely comeback by Fillon's and Macron crumbling will likely be linked if it happens. (unless…see point 4 below)

The fact we are talking about Macron not making the second round as a shock shows just how unprecedented this election is.

Macron shot up to around 25 percent of the vote in opinion polls as Fillon blamed the press, the president and judges for the fake jobs scandal.

He has since dipped a bit but most polls had him around 23 % as the slight front runner ahead of Le Pen going into Sunday's first round.

Yet there is a possibility Macron's voters, at least those on the centre-right, considered the least faithful of all the candidates, could desert him on polling day and drift off to Fillon.

Pollsters have talked of a “hidden vote” (vote caché) in which voters themselves think they know who they are voting for but at the last minute, don't take the risk. Could Macron be victim of this phenomenon? 

3. Could leftist Jean-Luc Mélenchon upset the apple cart?

Who said the left didn’t have a candidate with a fighting chance?

While the Socialist party candidate Benoit Hamon’s campaign has floundered, the man normally to the left of him, Jean-Luc Mélenchon the reformed firebrand, has once again excelled.

The fiery orator has risen in the polls in recent weeks thanks in the main to two polished performances in live debates.

Opinion polls now put him up at around 19 percent of the vote in the first round, level with François Fillon, a scenario that would have been unthinkable to the right a few months ago.

The question is can Mélenchon’s recent momentum take him over the finish line and into the second round.

It’s worth noting Mélenchon enjoyed the same momentum in the run up to the first round in 2012, when polls put him at 16 percent, just behind Le Pen. In the end he gained 11 percent of the vote.

4. Le Pen doesn't make the second round…?

Since Donald Trump’s victory in the United States and the surprise Brexit referendum result, a Le Pen victory is the shock that everyone has been talking about, or even expecting to happen.

Forty years now Le Pen has been almost guaranteed to make the second round given her record score in the 2015 regional elections and the polls which have had her as a frontrunner for months.

But in recent weeks her campaign has tailed off. She hasn't exactly slumped in the polls, but support appears to have dripped slightly. She was at 28 percent weeks ago and has since fallen to 22 percent.

Has she run out of steam? Realizing she was struggling she went back to basics in the last week of the campaign by concentrating on her core selling points of immigration, islam and identity.

The result was some of the most hardline speeches she has given with analysts comparing the febrile atmosphere of her rallies to those held under her father Jean-Marie Le Pen when he was leader.

As in 2012 Le Pen may end up scoring higher than the last polls suggested as voters come out of hiding to put her name in the ballot box.

But it's also quite possible many working class voters, who form a core of her base, have been tempted by the rousing performances of hard-leftist and fellow anti-establishment candidate Jean-Luc Mélenchon. 

or…. 5. The doomsday scenario 

This would be the shock to end all shocks. Even bigger than when Le Pen's father Jean-Marie stunned France by making it to the second round in 2002.

5. Whatever happens it will be a shock.

With or without one last twist the result of the 2017 presidential election will be a shock, explains Edouard Lecerf from Kantar Public.

“Whoever the candidate is who is elected president of the Republic, it will be momentous,” he said.

“If it’s Marine Le Pen, it’s completely incredible. If it’s Emmanuel Macron, who’s only been in politics for two years, it’s incredible. If it’s François Fillon after everything that has happened, then it’s also an incredible result.”