Czech teenager Kvitova upsets Safina

Little-known Czech teenager Petra Kvitova shocked world number one Dinara Safina 6-4, 2-6, 7-6 in a dramatic third-round upset at the US Open on Saturday.

Kvitova, 19, won the final-set tiebreaker 7-5 when top seed Safina floated a backhand long to end the two-hour, 34-minute affair on Louis Armstrong Stadium.

The loss marked the first time this year that the 23-year-old Safina had failed to reach at least the semi-finals of a Grand Slam tournament.

Serving at 5-6 in the third set, the 72nd-ranked Kvitova saved three match points to force the tiebreak on a cool night at Flushing Meadows.

Kvitova bagged three straight points in the tiebreaker to take a 5-2 lead. Although Safina trimmed the lead to 6-5, Kvitova won the final point on the Russian's serve to seal the biggest win of her young career.

When the match ended, Kvitova shrieked with delight before walking to the net to face Safina. The match ended at 12:47 a.m. local time inside a half-filled stadium.

"It's amazing here," she told the crowd. "I love New York."

Kvitova advances to play 50th-ranked Yanina Wickmayer of Belgium in the last 16.

For Safina, the defeat marked the end of a tumultuous Open in which she was pushed to three sets in each of her previous two matches.

She had 39 unforced errors, nine double faults, and only 12 winners against Kvitova, while the hard-hitting Czech had 59 errors among her 47 winners.

Oudin shocks Sharapova

Meanwhile, Melanie Oudin's fairytale US Open continued in spectacular fashion when the 17-year-old American ousted former champion Maria Sharapova 3-6, 6-4, 7-5 in a third-round match.

When Oudin ended the two-hour, 58-minute affair with a crosscourt winner she raised her weary arms and dropped her racket while the capacity crowd of 23,000 roared in delight.

Sharapova, the 2006 Open winner, helped Oudin's cause by double-faulting 21 times. There were six consecutive breaks until Oudin held serve to win the match.

Oudin, who upset fourth seed Elena Dementieva in the second round, advances to play 13th seeded Russian Nadia Petrova.

Isner upsets Roddick 

Big-serving John Isner upset fifth-seeded fellow-American Andy Roddick 7-6, 6-3, 3-6, 5-7, 7-6 to advance to the fourth round.

The 6-foot-9 (2.06m) Isner boomed in 38 aces and took the fifth-set tiebreak 7-5 to claim victory over the 2003 winner and this year's Wimbledon runner-up.