Murray out as big names progress
Zverev vulnerable but should progress
Djokovic among seeds getting tournament underway
Andy Murray was a big name casualty on day one as he was easily beaten by Alex De Minaur, and throwing into doubt his entire clay season.
However, former top 10 players Stan Wawrinka and Dominic Thiem did get through their opening round matches as did the likes of Matteo Berrettini, Diego Schwartzman and Roberto Bautista-Agut.
The remaining eight first-round matches take place on the Tuesday schedule, as do four second round clashes, including Andrey Rublev versus Jaume Munar, Stefanos Tsitsipas against Benjamin Bonzi and top seed Novak Djokovic, who faces the qualifier, Ivan Gakhov.
These three are all heavy favourites to progress, but the other match in the round looks much more competitive, so we'll start our run-through for Tuesday there.
Draper facing big step up on clay against Hurkacz
Jack Draper picked up a decent opening round win over the clay-courter Sebastian Baez, and now faces Hubert Hurkacz, who will have been grateful for a day off following his 39-game win over Laslo Djere.
With points long due to the slow conditions, the match lasted a fair bit in excess of three hours, and Hurkacz will be ruing his failure to convert numerous break point chances in the match to get the job done quicker.
Draper's win over Baez will have done the Brit's confidence a world of good after picking up an injury at Indian Wells, but has never really shown much aptitude, or desire to play on clay in his pro career.
He has a losing record in Challengers on clay, and has played just nine matches on the surface across both that tour and the ATP Tour.
Given this, I'm pretty surprised that Hurkacz is as big as 1.728/11 on the Exchange currently.
The Pole is running at in excess of 106% combined service/return points won on the surface in the last 12 months, and was good enough to reach two Masters quarter-finals (including here) last season.
If he can take his break point chances this time, I'd expect Hurkacz to get the job done.
Zverev and Dimitrov short-priced as heavy favourites
In the first round, Alexander Zverev versus Alexander Bublik looks the match of the day and Zverev is just 1.192/11 to get past the Kazakh.
I'm far from a buyer of Zverev right now - he's still to beat a top 50 player this year on the ATP Tour following his injury comeback - and he's coming off a defeat at a similar market price to Taro Daniel in Miami a few weeks ago.
However, Bublik's clay numbers over the last couple of years are very mediocre indeed and even though Zverev looks short-priced, he should make it through. Tougher tests await.
Alejandro Davidovich Fokina versus Karen Khachanov looks another decent match with Khachanov having the recent form but Davidovich Fokina having better clay data since the start of last year, so perhaps it's not a huge surprise that the market is pretty split, with both player trading at 1.991/1 or 2.01/1.
If pushed, I'd prefer Davidovich Fokina at prices.
Finally, I wonder if Grigor Dimitrov could be a little vulnerable against Ben Shelton. Yes, Shelton is in a similar position to Draper having had very little pro experience on clay, but the American possesses a strong serve and if that's firing, could keep matters close at the very least.
However, his limited return game means that if he is to succeed, key point performance will be vital.