U.S. Open Day 8 preview

Rafael Nadal will attempt to continue his stunning run on hard courts this year. (Adam Davis/Icon SMI)

NEW YORK -- Here are the storylines and matches to watch on Day 8 of the U.S. Open. CBS begins its coverage at 11 a.m. and ESPN2 picks up the night session at 7 p.m. Click here for the order of play.

Storylines

Roger Federer and Rafael Nadal gunning for the quarterfinals: Federer and Nadal are one win away from a quarterfinal clash on Wednesday. Federer will play 19th-seeded Tommy Robredo first (third match, Arthur Ashe Stadium), while Nadal faces Philipp Kohlschreiber (first night match, Arthur Ashe Stadium). Federer, who is 10-0 against Robredo, has looked very sharp through three rounds. Nadal is 9-1 against Kohlschreiber and hasn't lost a match on hard courts this year. It's looking like the dream quarterfinal, which would be the the 32nd meeting between Federer and Nadal, is in the cards.

Mike and Bob Bryan's Grand Slam quest: The twins came back from a set and a break down to beat Daniel Nestor and Vasek Pospisil 6-7 (1), 7-5, 6-2 on Sunday to keep their quest of completing the calendar-year Grand Slam alive. Next up is the British team of Colin Fleming and Jonny Marray (second night match, Arthur Ashe Stadium). No doubles team has completed the Grand Slam since 1951.

Alison Riske and Camila Giorgi go for encores: The two youngsters stole the headlines in the third round, with Riske, an American wild card ranked No. 81, defeating 2011 Wimbledon champion Petra Kvitova 6-3, 6-0 and Giorgi, an Italian qualifier ranked No. 136, ousting former U.S. Open finalist Caroline Wozniacki 4-6, 6-4, 6-3. Both have winnable matches in the fourth round. Riske  gets the big stage, taking on No. 48 Daniela Hantuchova in the first match on Arthur Ashe Stadium. She's 0-2 against Hantuchova, but the 23-year-old from Pittsburgh is playing the best tennis of her career. Giorgi, 21, has, on paper at least, a tougher test against a 2012 quarterfinalist, No. 10 Roberta Vinci (first match, Grandstand). If Giorgi zones in on her forehand the way she did against Wozniacki, she's capable of extending her run.

Matches to watch

Victoria Azarenka vs. Ana Ivanovic (second match, Arthur Ashe Stadium): Can Ivanovic finally break through again in a Grand Slam tournament? She's made only one quarterfinal at a major since winning the 2008 French Open. The Serbian former No. 1 narrowly escaped in the third round, coming back to defeat Christina McHale 4-6, 7-5, 6-4.  Azarenka, who leads the head-to-head 4-2, defeated her 6-0, 4-6, 6-3 earlier this summer in Carlsbad, Calif., but the loss gave Ivanovic confidence that she could beat Azarenka.

"I really want to play against the best and challenge myself, because I'm ready to take them on," Ivanovic said after her third-round win.

If Ivanovic plays up to her potential, she definitely has a chance to pull off  a bracket-busting win.

Milos Raonic vs. Richard Gasquet (third match, Louis Armstrong Stadium): Raonic has been solid through the first three rounds and he'll get his first big test against No. 8 Gasquet of France. The 22-year-old Canadian won their only previous match, in Cincinnati last year. In a quarter that was weak to begin with and only got weaker due to upsets, I like Raonic's chances to make the semifinals. Gasquet will try to improve on his 1-15 record in the fourth round of majors.

Simona Halep vs. Flavia Pennetta (first match, Louis Armstrong Stadium): Romania's Simona Halep is for real. The 19th-ranked Halep looks poised to make her first Slam quarterfinal. Pennetta, who has matched her fourth-round showing at Wimbledon, leads the head-to-head 2-0, but Halep is brimming with confidence after winning her fourth title of the season, at the New Haven Open the week before the U.S. Open. Serena Williams (eight) is the only player with more titles than Halep this year.

This post has been updated to correct the head-to-head record between Simona Halep and Flavia Pennetta.