NEW YORK: Reigning Olympic champions Rafael Nadal and Elena Dementieva got their US Opens off and running Monday, facing stiff challenges from a pair of unseeded players.

Nadal, who goes into a Grand Slam ranked No 1 in the world for the first time, outlasted Bjorn Phau 7-6(7/4), 6-3, 7-6(7/4) on day one of the 20.6 million dollar tournament.

Like Nadal, Dementieva came out shaky but finished on a winning note by brushing aside Akgul Amanmuradova in straight sets. The fifth seed Dementieva hopes her 6-4, 7-5 victory is a stepping-stone to better things.

The 22-year-old Nadal, of Spain, fired seven aces and hammered 37 winners but it wasn’t the opening statement he had hoped for, as he needed almost three hours to beat 146th ranked journeyman Phau.

Nadal moves through to the second round where he will face Ryler De Heart who surprised Belgium’s Olivier Rochus in a five setter 7-6(7/4), 5-7, 6-4, 3-6, 6-4.

Nadal has his gold medal to go with his victories at the French Open and Wimbledon this year. Last week he surpassed Roger Federer as the world’s top ranked player after spending a record 160 weeks as No 2.

The sky is the limit for Nadal who has eight titles this season but has never made it to a hardcourt Grand Slam final.

Scottish sixth seed Andy Murray, who is looking to improve on his fourth-round finish last year, rolled to a 6-3, 6-4, 6-0 win over Sergio Roitman in his opening match in the final Grand Slam of the season.

On the women’s side of the draw, Dementieva, second seed Jelena Jankovic, third seed Svetlana Kuznetsova, China’s Li Na and 23rd seeded Lindsay Davenport, of the US, all advanced.

Dementieva had four double faults and only three aces but made less unforced errors, 20 to 32, than her opponent in the 88-minute. Dementieva next faces France’s Pauline Parmentier.

Li got off to a disastrous start before coming from behind to beat Israel’s Shahar Peer 2-6, 6-0, 6-1. True to her history of not surrendering easily, Li converted five of six break point chances and won 58 percent of her second serve points to Peer’s 42 percent.

The lowest seed to get knocked out on the opening day was 10th ranked Anna Chakvetadze who lost to Russian compatriot Ekaterina Makarova 1-6, 6-2, 6-3.

In the night match, former world number one Jankovic launched her quest to reach her first Grand Slam final, cruising past American wild card Coco Vandeweghe 6-3, 6-1. This is the sixth straight US Open for second seeded Jankovic who moves through to the second round where she will face Swede Sofia Arvidsson who beat China’s Yan Zi 6-2, 6-4.

Men’s second seed Federer, women’s world No 1 Ana Ivanovic and the Williams sisters were playing their first round matches later on Tuesday.

Monday’s selected results (x denotes seed):

Women, 1st rd: Elena Dementieva (RUSx5) bt Akgul Amanmuradova (UZB) 6-4, 7-5; Patty Schnyder (SUIx15) bt Anastasia Pivovarova (RUS) 6-3, 3-6, 6-3; Aravane Rezai (FRA) bt Asia Muhammad (USA) 6-2, 6-4; Marion Bartoli (FRAx12) bt Galina Voskoboeva (RUS) 6-2, 6-3; Lindsay Davenport (USAx23) bt Aleksandra Wozniak (CAN) 6-4, 6-2; Svetlana Kuznetsova (RUSx3) bt Shuai Zhang (CHN) 6-4, 6-2; Li Na (CHN) bt Shahar Peer (ISRx24) 2-6, 6-0, 6-1; Victoria Azarenka (BLRx14) bt Klara Zakopalova (CZE) 6-2, 6-1; Ekaterina Makarova (RUS) bt Anna Chakvetadze (RUSx10) 1-6, 6-2, 6-3; Vera Zvonareva (RUSx8) bt Barbora Zahlavova Strycova (CZE) 6-4, 6-3; Jelena Jankovic (SRBx2) bt Coco Vandeweghe (USA) 6-3, 6-1.

Men, 1st rd:

Gael Monfils (FRAx32) bt Pablo Cuevas (URU) 6-4, 6-4, 6-1; David Ferrer (ESPx4) bt Martin Vassallo Arguello (ARG) 7-6(7/1), 6-2, 6-2; Gilles Simon (FRAx16) bt Marcel Granollers (ESP) 6-4, 6-3, 5-7, 6-2; David Nalbandian (ARGx7) bt Marcos Daniel (BRA) 6-1, 6-2, 6-4; Kei Nishikori (JPN) bt Juan Monaco (ARGx29) 6-2, 6-2, 5-7, 6-2; Stanislas Wawrinka (SUIx10) bt Simone Bolelli (ITA) 7-6(7/5), 6-3, 6-3; Andy Murray (GBRx6) bt Sergio Roitman (ARG) 6-3, 6-4, 6-0; Rafael Nadal (ESPx1) bt Bjorn Phau (GER) 7-6(7/4), 6-3, 7-6(7/4); Juan Martin Del Potro (ARGx17) bt Guillermo Canas (ARG) 4-6, 7-6(7/0), 6-4, 6-1; James Blake (USAx9) bt Donald Young (USA) 6-1, 3-6, 6-1, 4-6, 6-4.