Day 9: What to expect at US Open

Djokovic, Kerber aim for semi-finals at US Open

Men's top seed Novak Djokovic and women's number two Angelique Kerber look to book berths in the last four of the US Open as the quarter-finals of the year's last Grand Slam get underway on Tuesday.

Kerber, who nearly ended Serena Williams' long run as world number one last month in Cincinnati, tries to stay on track for a possible winner-take-all match with the American in the finals when she goes against Roberta Vinci.

The German, who won the 2016 Australian Open and was runner-up to Williams at Wimbledon, has yet to drop a set at Flushing Meadows.

The seventh-seeded Vinci could be a difficult hurdle for Kerber. The Italian, last year's US Open runner-up, has split four career matches with Kerber and won two of three on hard courts.

The other women's quarter is a battle of none seeds with former world number one Caroline Wozniacki playing Anastasija Sevastova of Latvia, who upset French Open winner Garbine Muguruza and Britain's 13th-seeded Johanna Konta along the way.

Men's world number one Djokovic, who has hardly been tested after receiving a second-round walkover and benefited from a first-set retirement in the third round, faces French veteran Jo-Wilfried Tsonga in his quarter-final.

The Serb leads their head-to-head 15-6 and has won 11 of his last 12 matches against Tsonga dating back to 2012. Tsonga's wins include a five-set quarter-final victory over Djokovic at the 2010 Australian Open.

The other men's quarter on Tuesday is an all-French affair with 10th-seeded veteran Gael Monfils taking on 22-year-old Lucas Pouille, who shocked 14-time Grand Slam singles winner Rafael Nadal in five sets in the fourth round.