New York, Sep 4 (DPA) Shaky top seed Dinara Safina turned in another patchy performance to escape with a victory, while American Melanie Oudin produced the shock of the event so far with a 5-7, 6-4, 6-3 knockout of fourth seed Elena Dementieva Thursday.

It was hit-or-miss for Safina, troubled by doubts over her status as a world number one who has yet to win a Grand Slam title.

The Russian got past Kristina Barrois of Germany 6-7 (5-7), 6-2, 6-3, no thanks to 15 double faults and 38 unforced errors in their second-round match-up.

The two-and-a-quarter-hour struggle was turned in the seed's favour by 43 unforced errors from her opponent.

Dementieva, the 2004 losing finalist, had been tipped as an outside title favourite, given the apparent knee injury to third Venus Williams and Safina's lack of confidence after losing three Grand Slam finals in two seasons.

But the Russian failed to come through in the clutch as 70th-ranked Oudin continued to surprise after Wimbledon fourth round performance just weeks ago.