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Former champion Venus Williams was a lopsided first-round loser at the Italian Open tennis event.

Promising British left-hander Laura Robson whipped the former world No. 1 and seven-time major champion Williams 6-3, 6-2 on a sunny, windy day on the red clay at Foro Italico. The American star was the Rome titlist back in 1999 and runner-up in 1998.

The former Wimbledon junior champion Robson is rewarded with a second-round match against Williams' younger sister Serena -- the current world No. 1 superstar who's fresh off her clay-court title in Madrid last week.

"She's really young, still," Serena said of Robson. "She's just so free and she looks great on the court and she's so smooth and she's a lefty, so that just adds a notch to her whole level. I've never played her before. I've always wanted to. So I have a tough second-round match."

Ninth-seeded former U.S. Open champ and 2011 Rome runner-up Samantha Stosur moved on Monday by tackling Taiwan's Su-Wei Hsieh, 6-2, 6-3.

Stosur lost to reigning two-time Rome champion Maria Sharapova in the final here two years ago. Sharapova beat Chinese star Li Na in last year's finale.

Former world No. 1 Jelena Jankovic advanced by besting Bulgarian Tsvetana Pironkova 6-3, 6-0, while Romanian qualifier Simona Halep lambasted former French Open champion and two-time Rome runner-up Svetlana Kuznetsova of Russia 6-1, 6-1, and Kiki Bertens erased former French Open winner and long-time Italian crowd favorite Francesca Schiavone 7-6 (7-5), 6-1. Jankovic was the back-to-back Rome titlist in 2007 and 2008 and runner-up in 2010.

Meanwhile, American qualifier Melanie Oudin moved on by beating Russian Ekaterina Makarova 2-6, 7-5, 4-2, retired, and German slugger Sabine Lisicki defeated American qualifier Mallory Burdette 6-1, 6-2.

Also advancing were Japan's Ayumi Morita, Spanish qualifier Garbine Muguruza, Italian wild card Nastassja Burnett, and Chinese Peng Shuai. Burnett topped 2008 Rome runner-up Alize Cornet of France, 6-2, 6-2.

This week's top seeds are current and/or former world No. 1s -- Serena Williams, last week's Madrid runner-up Sharapova and Australian Open champion Victoria Azarenka. Sharapova will meet the aforementioned Muguruza in the round of 32 on Wednesday.

Tuesday's schedule will feature second-round matches for the reigning Wimbledon and U.S. Open champion and former Rome titlist Serena, fourth-seeded Wimbledon runner-up Agnieszka Radwanska and eighth-seeded former Wimbledon champ Petra Kvitova.

Also on Tuesday, first-round matches will come for former No. 1s Caroline Wozniacki and Ana Ivanovic and American Sloane Stephens, who will take on Italian favorite Flavia Pennetta.

The winner of this $2.4 million event will collect $445,000.