TENNIS US OPEN CHAMPIONSHIPS: WOMEN'S FOURTH seed Elena Dementieva became the first big-name casualty of the 2009 US Open when American teenager Melanie Oudin claimed another grand slam scalp yesterday.

Oudin, 18 later this month, had caused a shock at Wimbledon earlier this summer when she knocked out Jelena Jankovic in the third round and the world number 70 added the 2008 Olympic champion to her list of victims at Arthur Ashe Stadium with a 5-7, 6-4, 6-3 upset victory.

Having allowed Oudin to level the match at 1-1, Olympic champion Dementieva quickly allowed the American to take the initiative in the final set when the Russian’s serve was broken in the second game.

Dementieva broke straight back and as the players took a break at the change of ends, Oudin called for a trainer to receive a medical timeout for treatment to her left thigh, which had been bandaged.

Returning to play with the thigh now heavily wrapped, Oudin showed no ill effects as she sent over a cross-court forehand winner to earn double break point and she took the game at the first opportunity when Dementieva sent a forehand long.

There was another twist at 15-0 in the first game, when Oudin suddenly clutched her thigh and winced in apparent pain as she prepared to serve but she continued to huge cheers from the Ashe crowd.

Oudin, though, could not prevent Dementieva earning two break points and though she saved the first of them, a forehand down the line curved out of play and the initiative was lost once more.

The American received more treatment at the next break and when play resumed it was once again the server who got into trouble as Oudin earned double break point.

She netted a baseline forehand with the first opportunity but got the vital breakthrough when she finished a long rally with an overhead winner to go 4-2 up.

Oudin held serve to leave Dementieva needing a hold to save the match.

Dementieva got safely through the game but left Oudin serving for the match and the American quickly gave herself triple match point. The fourth seed saved the first two in clinical fashion but then Oudin sent down a big serve wide to the Russian’s backhand and the netted return sparked loud celebrations.

Top seed Dinara Safina came through another shaky match to reach the third round with a win over Kristina Barrois.

Thee Russian took two hours and 13 minutes to eke out a 6-7 (5/7), 6-2, 6-3 victory.

Safina, who gave up 15 double faults and committed 38 unforced errors to 36 winners, had been out of sorts from the start, opening the match by having her serve broken before breaking straight back.

The first set went with serve from there and Barrois just managed to hold her serve to take it into a tiebreak.

Safina was again in trouble as Barrois took a mini-break to lead 5-4 and her serve let her down at the decisive moment when a double fault, her sixth, gifted the German the set after 57 minutes.

Safina came out for the second set all steamed up and broke Barrois to love but at 2-1 up the top seed served another fault before netting a forehand as the set got back on serve.

That changed quickly though as Safina took the next three games in a row and served for the set at 5-2, pulling level with Barrois at 1-1 when the German mis-hit a crosscourt backhand wide.

The Safina serve was continuing to undermine the Russian and she began the third set as she had the opener, by failing to hold the second game.

Luckily for her, Barrois was serving just as poorly and she was broken in the next game.

Safina levelled up the set at 2-2 with her next hold and at 3-2 down produced perhaps her best service game of the match so far, back-to-back aces and then another big serve angled in to the Barrois backhand helping her to the game. The victory finally looked assured but Safina was not out of the woods yet. At 4-3 up she gave herself more work to do as she faced a triple break point, once again digging herself out of trouble to get to within a game of advancing to round three.

Then it was Barrios’s turn to crumble, the German quickly offering three match points and surrendering meekly at the first, a double fault handing the win to a far from convincing Safina.

In the men’s competition, Wimbledon semi-finalist Tommy Haas breezed into the third round with a 6-4 6-4 7-6 (7-3) victory over American Robert Kendrick.