Serena Williams and Madison Keys among five to watch at Wimbledon

We take a look at five players who could win Wimbledon this year from the women's side of the draw, where there have been some surprises in recent years.

Perhaps the biggest surprise is that world No 1 and top seed Serena Williams has not lifted the Venus Rosewater Dish since 2012, but she has been in imperious form this year and is halfway to completing a calendar Grand Slam.

Petra Kvitova is the only woman to beat Serena in 2015 and is the defending champion after winning Wimbledon for a second time last year.

But along with the top two seeds, who are the main contenders for the title at All England Club this year?

Serena Williams (Sky Bet odds: 7/4)

She may be a five-time champion, but Wimbledon has not been a happy hunting ground for Serena in the past couple of years. In 2013 she was beaten in the last 16 by Sabine Lisicki and last year she was stunned by Alize Cornet in the third round before a bizarre withdrawal in the doubles when she appeared to be unwell.

Still, she will start as the clear favourite to lift the trophy and secure the third part of a calendar Grand Slam. Serena showed at the French Open that even when she is not at her best she is still good enough, and mentally tough enough, to overcome the rest of the field.

In 2015 she is a remarkable 32-1 – her only loss (barring two walkovers) coming against Petra Kvitova in Madrid – and she is two majors away from tying Steffi Graf’s Open era record of 22.

Not that she is too focused on records: "I think it will be awesome, but at the end of the day it’s pretty awesome to have 20...I haven’t done great at Wimbledon the past two years, so I'm going to take it a day at a time there. That’s the one (Grand Slam) I have been struggling at, so hopefully I will be able to play a little better there.”

If Serena does indeed play "better" then it's difficult to see who is going to stop her. 

Petra Kvitova (Sky Bet odds: 4/1)

The 2011 champion won Wimbledon for a second time last year after a hugely impressive display against Eugenie Bouchard in the final. Kvitova took just 55 minutes to power past the Canadian 6-3 6-0 and confirm that grass is perfectly suited to her game.

Seeded No 2 this time around, the 25-year-old’s preparations were disrupted by illness that forced her to withdraw from the Aegon International in Eastbourne. “I don’t need antibiotics so that’s a good sign. I have a sore throat. I have to stay in bed, drink tea and rest,” she said. “I hope to be fine for Wimbledon. I'll stay here in Eastbourne and then slowly move to London.”

My favourite shot at Wimbledon is the serve because I'm left-handed. This is always the most important shot for me. Whether I am facing a break point, or I have a match point, I have that serve, and that's great.

If Kvitova is fully recovered for the All England Club she is sure to be a major threat again. The Czech has at least made it to the quarter-finals in the previous five years, says she “loves” playing on grass and counts Wimbledon as her “favourite tournament”.

She has also done something no other woman has done this year, and something she had never done before: beaten Serena Williams.

Maria Sharapova (Sky Bet odds: 9/1)

After bursting on to the scene with her maiden Grand Slam victory at Wimbledon in 2004, Sharapova has not enjoyed the success that many might have expected at All England Club. Since 2006 she has only gone past the fourth round once and on three occasions she has been beaten in the second round.

In 2015 she has won tournaments in Brisbane and Rome but otherwise the season has not gone according to plan. At the Australian Open she was beaten in the final by Serena Williams and at the French Open she suffered a surprise last-16 defeat to Lucie Safarova.

Following that loss, Sharapova decided to take some time out ahead of Wimbledon and not play any competitive warm-up tournaments, instead going to the exhibition event at Hurlingham.

While she has said that she "she will be ready" for Wimbledon, her seeding means she could have to beat Serena Williams and Petra Kvitova to lift the trophy.

Madison Keys (Sky Bet odds: 50/1)

One of the brightest young talents in the game, Keys has earned praise from all corners of the game this year. Serena Williams said she can be “the best in the world” after beating her in Australia while coach Brad Gilbert said he believes the 20-year-old will “become No 1 in the world in the next 24 to 36 months and win Grand Slams.”

As of yet, Keys has only one title in her name – on the grass at Eastbourne last year – and she is ranked outside the top 20 in the world.

She’s got a huge serve. If she can figure out the movement on the court, she's going to have a shot at going deep at an event like Wimbledon.

There is no doubt, though, that she has potential and has the game to pose problems on grass. She possesses powerful ground strokes, one of the fastest serves on the WTA Tour and showed mental toughness when she fended off nine match points in defeat to Serena earlier this year.

Unfortunately for the American her preparations for Wimbledon were disrupted by a bout of flu and then an opening round defeat to Belinda Bencic at Eastbourne. “In a perfect world you want four or five matches before you go into Wimbledon,” she said afterwards. "But people have done it before where they don't have very many matches and some people don't play any. I'm just going to get lots of practice down at Wimbledon and be prepared for that.”

Sabine Lisicki (Sky Bet odds: 18/1)

There can be few players on the WTA Tour who were looking forward to the grass courts this year as much as Lisicki.

To say the German’s 2015 has been disappointing so far would be an understatement. She has lost in the opening round on seven occasions, been ‘double-bagelled’ in Stuttgart – losing 6-0 6-0 to Zarina Diyas – and has slipped down to 18 in the rankings.

But there is something about the grass that brings out the best in the 25-year-old.

In her first tournament on the surface this year in Birmingham she reached her second semi-final of the season and also set a world record for aces in a women’s singles match with 27.

“I just feel so much at home on grass,” she has said. “As soon as I practised on grass for the first time, it just felt like I've been on it my whole life, so it’s always a nice feeling to come back and play on grass - I really enjoy it.”

With a huge serve behind her, Lisicki has reached at least the quarter-finals at Wimbledon for the past five years, coming closest to winning it when she was beaten in the 2013 final by Marion Bartoli.

Seeded 18th this year, the German will be a big danger in the draw and it would not be a surprise to see her reach the latter stages at All England Club again.

Best of the rest

Like her fellow German Lisicki, Angelique Kerber’s game seems to be suited to grass. She has fared better at Wimbledon than at any other major, reaching the quarter-finals last year and semis in 2012. She also comes into the tournament on the back of winning her first grass court title in Birmingham against Karolina Pliskova. The big-serving Czech looked impressive in defeat and could also be one to look out for at Wimbledon.

Aged just 17, Ana Konjuh became the youngest WTA title winner since 2006 when she lifted the title in Nottingham recently. The Croatian has a big serve, says that grass is her favourite surface and came through qualifying to reach the third round at Wimbledon last year.

Lucie Safarova made it to the semi-finals at All England Club in 2014 and will be hopeful of another strong showing after her impressive display at the French Open while Belinda Bencic is certainly one to watch after winning the Aegon International in Eastbourne. The 18-year-old is a former junior winner at Wimbledon, reached the third round in 2014 and made the final on the grass in 's-Hertogenbosch this year.