Australian Open (Women): Underdogs Are Still a Bad Bet — Just Less Than Men

These are the historical results for Women’s performance at the Australian Open since 2011.

I've done the same analysis I did for the Men.

It’s since 2011, because I couldn’t get Pinnacle closing odds for 2010.

Long-Term View: Australian Open (Women) 2011–2025

I gathered 1,884 valid matches/bets for this period. Some odds were missing, and I also removed matches where the final odds for the favorite and the underdog were exactly the same.

And these are the results:

We can see that if we had bet $100 on all Favorites at Pinnacle’s closing odds, we would have lost around $5,100, with a yield/ROI of roughly -2.7%.

But if we had done the same on all Underdogs, we would have lost around $19,000, which is a yield of -9.8%.

That said, around bet number 1,600, underdogs’ performance improves a lot. And that coincides with the Australian Open 2023.

Over the last 3 Australian Opens (2023 to 2025, 505 matches), underdogs show a +4.1% yield, while favorites are at -7.4%. This is very likely just variance, and underdogs will probably trend down again over time.

Breaking Underdogs and Favorites into Groups

Now, let’s go one step further, like we did with the men, and split the data into 3 groups, ordered from lower to higher underdog odds, to see if there’s any meaningful difference.

The 1,884 bets are split into 3 equal groups of 628 bets, sorted by odds. The odds ranges are simply defined by splitting the sample into 3 equal parts.

The key takeaway is that the “soft” underdogs have a positive yield of +5.9%, while the longshots show a brutal -35.9%.

The first one is quite interesting... although it could be variance, who knows? We would need a higher sample.

But the second one is so extreme that it’s clearly the Favorite–Longshot Bias in full effect. The highest prices carry the highest margin for the bookmaker — in this case, Pinnacle.

Conclusions

So yes: in the women we also see the Favorite–Longshot Bias. This is usually the rule when we talk about high odds, although there are some nuances — and some of them are important — that I’ll share with you over time.

Because WTA matches are best of 3 (vs best of 5 for men), the probability of upsets is higher, and underdog prices are naturally lower. That explains why the FLB effect is smaller in women than in men.

In the men, the overall underdog return was -20.1%, while here it’s -9.8%. In the longshot group, women are at -35.9%, compared to -45.8% in men.

Part of that difference is simply because the average price in that third group is more than 1 full point higher in the men’s sample.

To sum up: I wouldn’t bet too much on big underdogs in women either, because you’re still going against the trend. The difference is that, due to best-of-3, the effect isn’t as brutal as in the men’s side.