|Wozniacki reached the quarters by beating Sharapova as she aims for her first grand slam win [AFP]
Caroline Wozniacki cleared one of the major hurdles in her bid to win the women's US Open title when she downed an error-prone Maria Sharapova, who is still battling to regain her best form after struggling with injuries for the past two seasons.
The former world number one was soundly beaten 6-3 6-4 but contributed to her own downfall with 36 unforced errors and nine double faults, including three in successive points.
Dane Wozniacki was a surprise finalist last year but top seed this time around after an impressive season and the withdrawal of world number one Serena Williams, and is still on course for her first grand slam title after reaching the quarter-finals.
In the men's draw, 16-times grand slam champion Roger Federer is through to the quarter-finals and in majestic form, but most of his main rivals are too.
Only Andy Murray has made an early exit.
Federer booked his place in the last eight with a 6-3 7-6 6-3 win over Jurgen Melzer at the Arthur Ashe Stadium on Monday without ever having to play at his best.
His next opponent is Robin Soderling, the big-hitting Swede who ended Federer's French Open defence earlier in the season.
|Djokovic will face Gael Monfils in the quarters [AFP]
If he gets through that, Federer could then face Serbia's Novak Djokovic, who beat him in the semi-finals at the Australian Open in 2008.
There is also Rafael Nadal lurking on the other side of the draw if they both reach the final.
Soderling and Djokovic also moved through to the quarter-finals by winning on Monday.
The Swede overcame Albert Montanes, one of six Spaniards who made the last 16 of the men's draw, 4-6 6-3 6-2 6-3.
And world number three Djokovic demolished American Mardy Fish 6-3 6-4 6-1 and is steadily building momentum and confidence.
Sharapova was one of two former US Open champions from Russia that were beaten in straight sets.
Svetlana Kuznetsova also departed, losing 7-5 7-6 to diminutive Slovakian Dominika Cibulkova, leaving Vera Zvonareva to fly the flag.
Cibulkova will play Wozniacki in the quarters.
Federer is yet to drop a set in the tournament and hardly got out of second gear against Melzer.
He did have some problems with his serve and was broken once each in the first and third sets but was able to raise his game when it mattered.
Djokovic, getting better with each match after a shaky start to the tournament, provided a reminder of the form that saw him reach the final in 2007 then capture his maiden grand slam in Melbourne the following year with his best performance of the championship.
Next in line for Djokovic is Gael Monfils who overpowered his countryman Richard Gasquet 6-4 7-5 7-5 to become the first Frenchman in a decade to reach the US Open quarter-finals.
"It's very encouraging at this stage of the tournament that I'm raising my game and feeling more comfortable on the court," Djokovic said.
Soderling has developed a reputation of a giantkiller after beating Nadal at the French Open last year the Federer this season.
"I've played Roger many times. I know his game and he knows mine," Soderling said.
Estonia's Kaia Kanepi recovered from a horrendous start to wear down Belgium's Yanina Wickmayer 0-6 7-6 6-1 and reach the last eight against Zvonareva after the Wimbledon finalist outgunned Germany's Andrea Petkovic 6-1 6-2 in 67 minutes.