LONDON There is not much on a tennis court that will keep 13-times grand-slam champion Serena Williams awake at night, not even a Wimbledon fourth-round clash against a player who won the first set of her last match without losing a point.
The powerful Yaroslava Shvedova stands between the American and the quarter-finals on Monday, having dispatched Italy's Sara Errani 6-0 6-4 after winning the first 24 points of the match.
So in "the zone" was Kazakh wildcard Shvedova against the unfortunate Errani that she did not even realize that it was the first time in a grand-slam tournament that a set had been won in such a manner.
She will need to find the zone again, however, if she is to worry Williams, a player well known for her ruthless streak.
The American fired down 23 aces, a personal record, as she beat China's Zheng Jie in a tense three-setter on Saturday and knows a thing or two about the second week of majors.
The four-times Wimbledon champion was predicting a tougher test for Shvedova.
"She's such a solid player," Williams said. "I look forward to it. Hopefully I'll be able to win a point in the first set."
So far, on the evidence of this year's Wimbledon, few could argue with Frenchman Gilles Simon's controversial comment that the men's game is much more interesting that the women's.
While the men's singles has seen seismic upsets, late-night epics, marathon matches and fairytale comebacks, the women have been left largely in the shade.
That is not the natural habitat of Williams and world number one Maria Sharapova, who will both be aiming to move through the gears on last-16 day - known at Wimbledon as Manic Monday when all the men's and women's fourth-round matches are scheduled on a bumper day for the fans.
Sharapova, bidding to go one better than last year when she lost in the final to Petra Kvitova, has avoided any problems so far without hitting top form but will need to be sharp when she takes on Sabine Lisicki - the player she beat in last year's semi-finals.
Belgium's Kim Clijsters is still lurking dangerously in the field. Playing with the relaxed air of a woman on her farewell tour, she has yet to drop a set.
Angelique Kerber, though, will be a formidable test and the German's third-round victory over Christina McHale was her 43rd this season - more than any other player.
Defending champion Kvitova, who has reached the last 16 under the radar, faces Francesca Schiavone while Ana Ivanovic, looking a little more like the player who once reached world number one, faces second seed Victoria Azarenka.
(Editing by Clare Fallon)