Venue: All England Club, London Date: 21 June - 4 July
Coverage: Live on BBC One and Two, HD, Red Button, BBC Sport website (UK only), Radio 5 live, 5 live sports extra; live text commentary online and on mobile phones; watch again on BBC iPlayer
Full details of BBC coverage
Jankovic pulls out with injury
Third seed Caroline Wozniacki and fourth seed Jelena Jankovic bowed out of Wimbledon in differing fashion on a busy day of fourth round action.
Wozniacki was overpowered by Czech left-hander and world number 62 Petra Kvitova 6-2 6-0 in a mere 46 minutes.
Jankovic withdrew from her match with Vera Zvonareva with a back injury.
Second seed Venus Williams battled past Australian Jarmila Groth 6-4 7-6 (7-5) while Tsvetana Pironkova, qualifier Kaia Kanepi and Li Na also won.
The 20-year-old Kvitova bewildered Wozniacki on Court Two.
Kvitova, who had not won a match on grass before eliminating Sorana Cirstea in the first round, hit some stunning strokes to reach her first Grand Slam quarter-final.
"I play very well on the grass, and I play very fast," said the world number 62. "So she didn't play her game, so maybe that's why was quick."
Kvitova's next opponent is Kanepi, and she said: "Kanepi is playing very well right now. We play already three times, I think. Two I lost and one I won so we will see. It will be a tough match, but it's open."
Estonian Kanepi overcame Klara Zakopalova 6-2 6-4 in a match featuring two unseeded players.
It was already the furthest the 25-year-old's had gone run in a Grand Slam, beating her third round spot in each of the last two years at Wimbledon.
Jankovic grimaced continually as she fell 6-1 and 3-0 behind before calling for treatment. The Serb then continued briefly before ending the match.
Zvonareva, the former world number five who has dropped to 21 this year, will play Kim Clijsters in the last eight after she fought back to beat compatriot Justine Henin 2-6 6-2 6-3.
The Russian took the opening set 6-1 in just 24 minutes against Jankovic, who played with a heavily strapped thigh and had only one bright moment when she broke in the fifth game.
Wimbledon remains the only Grand Slam where the elegant 25-year-old has failed to reach at least the semi-finals of the singles, and she has now experienced problems in her last three campaigns at SW19.
I hadn't noticed anything until she called the trainer...She said something is really bothering her
Zvonareva on Jankovic's injury
Two years ago she complained about being placed on a court that was "in a parking lot" and remarked that she needed a helicopter to reach it from the locker room.
Then last year she was left feeling delirious and with blurred vision because of the searing heat and what Jankovic termed "women's problems."
There were no such problems for Williams, even though the five-time champion arrived 10 minutes late for her match on Court Two.
"I didn't know the procedure for Court Two, so I was waiting on someone to get me," Williams explained later. "No-one came. So eventually I just came out."
The American sealed the first set in 35 minutes, after Groth had a line call overruled when 4-5 down and then sent a volley into the net.
The 23-year-old, the first Australian for 20 years to reach the last 16 in both the French Open and Wimbledon, twice served for the second set but Williams took it to a tie-break.
Line technology helps Venus to victory
Williams, 30, surged 4-0 ahead but Slovakian-born Groth levelled at 4-4 before finally losing the extended set in 62 minutes when a forehand could only find the net.
"She has a really good serve, hits the ball really well and I was really pleased to close it out in the end," Williams added.
In the quarter-finals Williams will play Pironkova after the Bulgarian upset 11th seed and 2007 finalist Marion Bartoli 6-4 6-4.
Meanwhile, seventh seed Agnieszka Radwanska of Poland was beaten 6-3 6-2 by Li Na of China, seeded nine.
Li, who reached the quarter-finals in 2006, broke her opponent's serve at the first attempt and wrapped up the first set in just 30 minutes.
The 28-year-old was guilty of 19 unforced errors in the match, seven more than her opponent, but hit 28 winners to Radwanska's six.
She completed victory in an hour and seven minutes to set up a quarter-final against top seed and defending champion Serena Williams, who beat former champion Maria Sharapova,the 16th seed, 7-6 (11-9) 6-4.