By Alistair Watkins
BBC Sport at Wimbledon
Jankovic grew increasingly frustrated as her game fell apart
Jelena Jankovic crashed out of Wimbledon with a 6-3 6-2 fourth-round defeat against Tamarine Tanasugarn.
The second seed needed treatment early in the second set as her knee, which she hurt on Saturday, caused her pain.
The Serb made far too many unforced errors as she followed Ana Ivanovic and Maria Sharapova in going out.
Svetlana Kuznetsova's defeat later on ensured that for the first time at Wimbledon, none of the top four women's seeds had reached the last eight.
Afterwards, Jankovic, 23, expressed her anger at being scheduled early on Court 18.
"I don't know what they are doing to put Venus (Williams) on Court Two and I'm on 18, especially having an injury and asking for a favour to play a little bit later on in the day.
"They didn't do it. So it was quite hard. I was almost playing in the parking lot. I almost need a helicopter to go to my court.
"I think the scheduling is not right. I think the number one and two seeds should always be on the top show courts. The rankings show who deserves it."
Tanasugarn, who needed treatment for a lower back problem during her victory over Jankovic, now faces Venus Williams for a place in the semi-finals.
Williams, the defending champion, beat Alisa Kleybanova of Russia in straight sets and, following fourth seed Kuznetsova's defeat by Agnieszka Radwanska, must fancy her chances even more of facing her sister Serena in the final on Saturday.
Jankovic's fitness was always going to be an issue after she twisted her left knee during her battling victory over Caroline Wozniacki in the previous round.
Jankovic's leg was strapped up and she initially appeared to be untroubled, but the 31-year-old Tanasugarn kept her moving around the court more than she would have liked.
Two years ago I had to play qualifying. I was having a tough time. During that time I was thinking about stopping my career
The world number 60, who has lost six times in the fourth round at Wimbledon, broke at the third attempt in the sixth game of the opening set and Jankovic became increasingly frustrated as the set went her opponent's way.
Jankovic called for medical help at 2-1 down in the second set while Tanasugarn had treatment on her back at the same time.
The world number three, who has yet to reach a Grand Slam singles final, committed more and more errors as her knee continued to cause her difficulties.
And the dimuntive but determined Tanasugarn, despite struggling with her own serve, sent Jankovic crashing out in rapid fashion to reach the quarter-finals of a Grand Slam singles for the first time.
"Two years ago I had to play qualifying. I was having a tough time. During that time I was thinking about stopping my career," she said.
"I was struggling for the last couple of years and my ranking dropped to maybe 140, 130.
"During that time I was maybe burned out and was trying to play lots of tournaments. Now I've started to take more care of my body. I just started to play for fun and I'm enjoying it again."
Tamarine has surged up to 60th in the rankings, helped by winning a tournament on grass in the Netherlands earlier in June.