Lleyton Hewitt was back to his emotional best as he grunted and growled his way past South Korea's Lee Hyung-taik 5-7, 6-2, 6-2, 6-4 in the second round of the U.S. Open on Thursday.

The Australian sixth seed, champion here in 2001, recovered from an indifferent start to win in two hours, 42 minutes on his fourth match point.

Famed for his animated behaviour, the former world number one had retreated into his shell recently following a disappointing season, but the fist-pumping was once again on display on the Louis Armstrong court.

When he seized a break to go 5-4 up in the fourth set, he turned in celebration to his entourage courtside and strained so hard the veins in his neck bulged alarmingly.

There was still work to be done, however, for he was forced to save four break back points and endure seven deuces in the following game before finally clinching a hard-earned victory with an ace.

Also advancing was Thailand's Paradorn Srichaphan, who beat Dominik Hrbaty of Slovakia 6-4, 6-4, 6-3

Pierce battles past Dokic

A battling Mary Pierce clawed her way into the third round, taming 22nd seed Jelena Dokic 6-2, 6-7, 7-6.

Fighting back to fitness following two injury plagued seasons, a beefy Pierce showed glimpses of the power game that helped her to win Grand Slam titles at the Australian and French Opens.

Pierce put in a determined and draining two-hour performance to edge out the Yugoslav on a sun-baked centre-court.

Having dealt with abdominal, back and ankle injuries over the last two years, the 28 year-old Frenchwoman appeared to relish her time back in the spotlight.

Pierce cracked a sly smile when she broke Dokic with a cheeky drop volley to jump into a 5-2 lead on her way to taking the opening set.

But at 5-4 and serving for the match, Pierce could not close out the second set.

She squandered a match point and allowed Dokic to level the contest after the Yugoslav won the tiebreak 7-5.

With Dokic storming to a 5-2 lead in the third and serving for the match, Pierce appeared to be on her way out.

But the 64th ranked Pierce dug deep into her reserves, breaking the Yugoslav twice and forced the match to a decisive tiebreak.

This time Pierce grabbed her opportunity, taking the tiebreak 7-5 when Dokic's return sailed wide and long.

Pierce will now await the survivor of the match between Tathiana Garbin of Italy and Japan's Shinobu Asagoe.

Easy for Davenport, Federer and Clijsters

Third seed Lindsay Davenport followed title contenders Roger Federer and Kim Clijsters into the next round with the minimum of fuss.

The American, champion here in 1998, beat Italian Maria Elena Camerin 6-2, 6-4 in the first match of the evening session at Flushing Meadows.

"It felt good, I managed to get through relatively easily," Davenport told reporters after her second-round victory.

Earlier, Wimbledon men's champion Federer opened his U.S. Open campaign with a first-round win, Argentine Jose Acasuso retiring because of cramps with the Swiss player leading 5-7, 6-3, 6-3, 2-0.

Women's world number one Clijsters thrashed American Laura Granville 6-1, 6-1 in 49 minutes.

In the other match of the evening session, American James Blake clinically disposed of 27th-seeded Argentine Mariano Zabaleta 7-6, 6-3, 6-2 to reach the second round.

Mark Philippoussis was also in control. The 20th-seeded Australian beat Serb Janko Tipsarevic 6-2, 7-6, 6-4.

Clijsters, yet to win a Grand Slam crown, was sublime against Granville and was joined in the third round by ninth seed Daniela Hantuchova, who survived a late scare against Ukrainian Julia Vakulenko to win 6-0, 7-6.

Hantuchova will next meet Thai Tamarine Tanasugarn, who ousted 18th-seeded Swiss Patty Schnyder 6-4, 6-3.

Amelie Mauresmo also advanced, the fifth seed trouncing fellow Frenchwoman Stephanie Cohen Aloro 6-2, 6-2.