Ailing women's defending champion Petra Kvitova has not played since the French Open. Last year's finalist Eugenie Bouchard has not won consecutive matches since March. And world No. 3 Simona Halep has had an inconsistent season. With upsets on the cards, The Straits Times looks at three players outside the top 15 seeds who could shock at Wimbledon

SABINE LISICKI, 25 (GER)

• Seeding: 18
• Best performance: Final (2013)

She arrives at the All England club in decent form, reaching the semi-finals at the Birmingham Classic last week. There, she sharpened her most lethal grass-court weapon, hitting 27 aces past Belinda Bencic in her opener to set a record for most aces in a WTA match.

"Boom Boom Bine" also holds the record for the fastest serve in the women's game - a 210kmh winner. Her serve and powerful ground strokes have seen her compile a 36-13 career win-loss (74 per cent) record on grass.

Her win rate at Wimbledon (79 per cent) is even better.

CAMILA GIORGI, 23 (ITA)

• Seeding: 31
• Best performance: R4 (2012)

She won her maiden WTA Tour title earlier this month on the grass of Rosmalen, Netherlands in the Den Bosch Open.

Her aggressive playing style makes her a threat on this surface. Her first serves clock in at over 175kmh, and her second serves are just like her first. She goes for the lines, and hits each shot as hard as she can. In two of her last three trips to Wimbledon, an eventual finalist was needed to send her packing.

Reputations do not faze her though. She has beaten former world No. 1s Caroline Wozniacki, Maria Sharapova and Victoria Azarenka and could yet claim another famous scalp this fortnight.

MADISON KEYS, 20 (USA)

• Seeding: 21
• Best performance: R3 (2013, 2014)

She was just a teenager when she reached her first Grand Slam semi-final at January's Australian Open, proving her potential and ability to handle the big stage.

Although she has never been past the third round at Wimbledon, her offensive game is built for grass.

She possesses easy power, particularly on her serve and forehand, and is comfortable at the net.

Her first WTA Tour title came at the Eastbourne International last year, and she has improved since under the guidance of former world No. 1 Lindsay Davenport.

Long in the shadows of compatriot Sloane Stephens, Keys has emerged as the future of American women's tennis.