It's ladies singles semi-final day today, and with the tournament wide open, our tennis columnist, Dan Weston, returns to preview the action...
"In short, the market has been convinced that Halep is the better player for this event, but yet has ditched her for this particular match-up, and it's difficult to understand why."
Contrasting quarter finals on day 11 see Halep and Muguruza progress
Yesterday's matches in Paris saw Simona Halep fight back from the disappointment of losing the first set on a tiebreak against Angelique Kerber to take the next two sets in relatively facile fashion, while our selection, Maria Sharapova, disappointed in the extreme in her defeat to Garbine Muguruza, who created 12 break points and faced just one.
Such impressive data from this match has led to Muguruza being chalked up as a [1.89] favourite over Halep, and I want to discuss why I think this is an utterly bizarre line.
Muguruza status as favourite completely unjustified
Firstly, Halep has been the tournament favourite for virtually the entire event. She was prior to the draw and it took a gift draw for Elina Svitolina - which the Ukrainian was unable to exploit - for her to lose this status for the opening two rounds.
Furthermore, Halep's data on return yesterday was similarly strong, creating 17 break points on the usually strong Kerber serve across 15 return games, and it took a resolute performance by the German to take that first set to a breaker.
In short, the market has been convinced that Halep is the better player throughout this event, but yet has ditched her for this particular match-up, and it's difficult to understand why. Yes, Muguruza has won three of their four head to head meetings, but Halep has won their only clay clash, so the head to head series is pretty irrelevant to this match-up.
Clay data also in Halep's favour
In addition, when we look at the clay data for 2018, Halep should be a clear favourite. She's won 59.6% of service points, compared to 59.0% for Muguruza, and won 51.9% of return points, an edge of 4.3% over her rival today. This is also the case when looking at slightly longer term data as well.
I can only conclude that the market has grossly over-reacted to seeing Muguruza's beating of Sharapova yesterday afternoon, and made her a false favourite for this clash - Halep at [2.10] is today's recommendation.
Stephens an uneasy favourite against compatriot Keys
The second semi-final today sees a repeat of last year's US Open final between Sloane Stephens and Madison Keys, where Stephens blitzed her American counterpart. I mentioned several days ago that both players have a very high peak level on clay but it is Stephens with the more impressive data, both in the last 12 months and also here in the last two weeks.
My model priced Stephens as a [1.70] favourite here, so the current [1.57] is a little short, but not worth acting on to oppose her. It would need Keys to be in excess of [2.80] for her to be actionable value to take this.
Both players were relatively unfancied prior to the event having had patchy years prior to the French Open, but have been able to reproduce their previous high levels to get to this stage. In truth, whoever makes it through will be an underdog in any final, but they will definitely have a fair chance of lifting the trophy on Saturday afternoon.
Follow Dan on Twitter @TennisRatings
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