Serena Williams eats dog food but reaches Italian Open quarters

Serena Williams made herself ill after eating dog food hours before reaching the last eight of the Italian Open.

The world number one tried "a spoonful" of food meant for her dog, Chip, before beating fellow American Christina McHale in straight sets in Rome.

"I thought 'what the heck, I'm gonna try a piece, it looks good'," she said.

"Fast forward two hours, I just ran to the toilet like I thought I was going to pass out. It did taste weird. It tasted kind of like house cleaner."

Serena Williams celebrates with her dog after winning the 2013 Madrid Masters

In a video posted on Snapchat, Williams explained she sampled a dish of salmon and rice offered on a 'doggy menu' at her hotel.

"I force-swallowed it, said the 34-year-old American. "I don't know what they put in these dog foods, but Chip liked it.

"I don't think it's consumable for humans. They should have wrote that! So now I feel really sick. It was just a spoonful, but I don't feel so good."

Williams defeated McHale 7-6 (9-7) 6-1 and set up a meeting with Svetlana Kuznetsova, who beat fellow Russian Daria Gavrilova, in the last eight.

Johanna Konta began well but her opponent fought back to win

Elsewhere, British number one Johanna Konta was beaten in three sets by Misaki Doi in the third round.

Konta, 24, took the opening set but went down 4-6 7-5 6-2 to her 25-year-old Japanese opponent.

Doi, ranked 45 in the world, belied her position 22 places below the Australian Open semi-finalist to take victory.

Doi faces Swiss Timea Bacsinszky in the last eight.

Despite her defeat, Konta will arrive at the French Open as a seeded player. A year on from being ranked 143rd in the world, she is up to 23.

"I thought she played a very, very good level today and I didn't do quite enough to get her out of her comfort zone," Konta told BBC Sport.