Heavy favourites - outright market contenders dominate
With action from the bottom half of the draw on day one, there's some contenders for the title getting their tournaments started at Roland Garros on Sunday.
These include Ons Jabeur, who should ease past Magda Linette without too much difficulty, while Belinda Bencic should also do the same against Reka-Luca Jani.
Maria Sakkari is also priced as a very heavy favourite against the home player, Clara Burel, who will need to serve well if she has to have any chance to create an upset. A hold percentage of below 60% on clay in the last 12 months on the main tour is illustrative of the difficulty she is likely to face.
Bigger priced favourites - one to win and one to struggle
One player whose results have taken rather a downturn in recent years is Sloane Stephens, and the 2018 finalist is now ranked outside the top 50 (she was a career-high rank of three not so long after that 2018 final).
Stephens is now on a six match losing run, last week in Strasbourg losing as a 1.11/10 favourite against a player ranked outside the top 300.
On a bad run, she might find it tough against Jule Niemeier of Germany, who breezed through qualifying, dropping just seven games in six sets. Niemeier also won the Zagreb ITF event a few weeks ago, and last season almost beat Barbora Krejcikova in the Strasbourg WTA tournament in the semi-finals.
Considering all this, it's probably not surprising that Niemeier has been chalked up as the 1.42/5 favourite, and there's an argument to suggest she could start even shorter-priced.
Another favourite who comes into the event in good form is Jil Teichmann, who reached the semi-finals of Madrid several weeks ago and then the quarter-finals in Rome.
However, in Rome, Teichmann pulled out of her quarter final with a leg injury and it remains to be seen if that was just a precaution, as is often the case prior to a Grand Slam event.
On Sunday, Teichmann faces Bernarda Pera who also has done well of late, reaching the final of the Karlsruhe WTA Challenger event several weeks ago, and taking a set off Karolina Pliskova in Strasbourg this week also. If Teichmann does have injury issues, Pera is competent enough to take advantage and I think a longish odds-on price is a bit of a risk on the favourite.
Another underdog option - but injury doubts throughout
The final match I want to discuss is Elena-Gabriela Ruse against Elise Mertens, with Mertens drifting a little in the market, but still the favourite at [1.56 ].
Mertens has struggled in recent months with a leg injury, and didn't particularly convince on her return to tour in Strasbourg this week.
Opponent Ruse has also had some back trouble but, as with Pera, is competent enough to cause an upset if Mertens isn't fully fit. However, this match, and the general discussion today, illustrates the dangers of first-round matches in Grand Slams with numerous players having fitness issues.
Sometimes it's very difficult indeed to know which players are turning up with an injury just to get paid, or which players aren't badly injured and will be fine come the start of the tournament.