Sara Errani made an early exit from the WTA Internazionali d'Italia at the hands of qualifier Heather Watson on a miserable day for home hopes in Rome.
As four of the five Italian men competing in the corresponding ATP event on Monday were knocked out, Errani - the beaten finalist at this tournament in 2014 - joined compatriots Karin Knapp and Francesca Schiavone in bowing out at the first hurdle.
World number 18 Errani fought back from losing the first set to force a decider, but was then blown away as Watson triumphed 6-4 3-6 6-0.
Two other seeds were knocked out in round one, Elina Svitolina and Karolina Pliskova going down to Monica Puig and Daria Kasatkina respectively, but former champion Venus Williams, Lucie Safarova - the conqueror of Schiavone - and Ana Ivanovic came through their opening tests.
MIXED FORTUNES FOR VENUS
Seventeen years have passed since the elder Williams triumphed at this event, beating Mary Pierce in the final.
On Monday, the seven-time grand slam champion moved into round two in Rome with a hard-fought 6-4 6-3 win over Coco Vandeweghe.
However, there was disappointment for Williams later in the day when her first doubles outing alongside sister Serena since 2014 ended in a straight-sets defeat to the Slovenian pairing of Andreja Klepac and Katarina Srebotnik.
SERENA TO BEGIN AGAINST FRIEDSAM AT HER 'FAVOURITE STOP'
Serena Williams will begin her campaign against Anna-Lena Friedsam after the German got past an out-of-form Anna Karolina Schmiedlova on Monday.
Williams was forced to miss last week's Madrid Open due to flu, but regards Rome as a highlight of any season.
"This is my favourite stop on the tour. I have a lot of Italian friends and we hang out all the time, just do everything together and most of all the food here is great," the world number one told the WTA.
"This tournament is super important for me. Missing Madrid was tough - I wasn't able to play there but I'm really pumped to be here."
BEGU MAINTAINS FORM, BUT AZARENKA AWAITS
Irina-Camelia Begu was one of several Romanian players to shine in Madrid, reaching the quarter-finals before losing to Simona Halep, the eventual champion.
And Begu appeared high on confidence in her first match in Rome as she thrashed Margarita Gasparyan 6-3 6-0.
However, next up for Begu is a daunting second-round meeting with world number six Victoria Azarenka.
PUIG AND PEREIRA PULL OFF UPSETS
Puig and Teliana Pereira claimed two of Monday's more notable wins.
In eliminating Svitolina, Puig enjoyed success against a player ranked 40 places above her, while Pereira, ranked 90th, accounted for world number 41 Beck in straight sets to set up a meeting with Carla Suarez Navarro.