Four of the 16 women left are hoping to reach a major quarterfinal for the first time: Robson, Knapp, 19-year-old Monica Puig of Puerto Rico, and 20th-seeded Kirsten Flipkens of Belgium.
The No. 1-ranked Williams, naturally, is an overwhelming favorite to win the title. She is a five-time Wimbledon champion, including last year. She owns 16 Grand Slam titles all told, while the other 15 women in the tournament own two among them: Li's at Roland Garros, and Petra Kvitova's at Wimbledon in 2011.
Narrow the focus, and facing Williams becomes even more daunting. She is 46-2 this season and has won her past 34 matches, the longest winning streak for a woman since older sister Venus' 35-match run in 2000.
Consider this, too: Williams has won six titles in 2013, the same total as the other 15 women combined.
It's entirely possible that the toughest match she'll face the rest of the way will come Monday against 23rd-seeded Sabine Lisicki of Germany. Lisicki is a mediocre 16-15 at other Grand Slam tournaments, but 16-4 at Wimbledon, where her powerful serve is nearly as much of a threat as Williams' is on grass.
Of the women in action Monday, Lisicki leads the way by having won 93 percent of her service games in the tournament (Williams is next at 91). Lisicki's 202 aces this season rank second on tour only to Williams' 292.
Lisicki reached at least the quarterfinals the previous three times she appeared at the All England Club, including a semifinal run in 2011 that included victories over Li and Bartoli. A year ago, she beat 2004 champion and No. 1-ranked Sharapova in the fourth round.
When it was pointed out that everyone is pretty much ready to hand Williams the trophy, Lisicki smiled and recalled: "I was in that situation last year, when everybody was saying that Sharapova was the favorite. I'm probably going into that match being the underdog, but I like that."
"Probably" the underdog against Williams?
"Well, you have to play your best to beat her, that's for sure," Lisicki said. "But, you know, everybody's (a) human being."
Especially, it seems, at this particular edition of Wimbledon, marked by so many injuries and so many surprises.