Yevgeny Kafelnikov joined his fellow Russian Marat Safin in the last eight of the US Open on a rain-affected morning session yesterday, defeating France's Arnaud Clement 6-3 6-4 6-3.

Clement, who had played brilliantly in the previous round to beat Spain's Carlos Moya, displayed his immense frustration when 3-0 down in the third set by trying to hit a ball out of the Arthur Ashe stadium, and received a warning.

Almost immediately it began to spit with rain, and Clement was off like a scalded cat. Kafelnikov clearly wanted to play on but the rain increased and play was delayed for about an hour. On the resumption Clement, who was beaten in this year's Australian Open final by Andre Agassi, substantially increased the intensity of his play, pulling back one break. But is was all too late.

"I had the perfect game plan and I didn't want the rain to come. To get into the quarters is good, but it's about time I went beyond that," said Kafelnikov, the former French and Australian Open champion who has been one of the most consistent players of the past seven years. But it seems to be his nature to make things tough for himself in the early stages of grand slams, this being his first straight-sets win at the US Open since 1999. "It's a huge confidence booster."

When Safin crushed Pete Sampras in straight sets in last year's US Open final, with champagne and vodka flowing freely in the post-match celebration, tennis hailed a new hero and a new era. The young Russian appeared to have the power and the technique to rule the world, the one doubt - and it was a pretty big one - being whether he had the temperament to climb to the top and stay there.

Safin had the opportunity to finish last year as the world number one, but it was snatched from his grasp during the Masters Cup in Lisbon by Gustavo Kuerten, who has since gone on to win his third French Open title.

Safin buckled under pressure, suddenly looking shaky and nervous, while Kuerten grew in stature in Portugal, beating Andre Agassi and Pete Sampras, who meet each other tonight in the quarter-finals here.

Having won seven titles last year, Safin has failed to capture one this time round, finding life a perpetual struggle. So it was that he arrived in New York low on confidence and form, and with few hopes of successfully defending his only grand slam title.

Any early defeat threatened to evict him from the top 10, thereby reducing his earning power enormously, and this has appeared to concentrate his mind wonderfully. Victory against Sweden's Thomas Johansson, the number 14 seed, swept Safin through to a quarter-final against Argentina's Mariano Zabaleta, and then a possible semi-final against either Agassi or Sampras.

His troubles began in the desert when he reached the final of the Dubai Open but had to retire when a set and 3-1 down against Spain's Juan Carlos Ferrero with a bad back.

The 21-year-old Russian, who has the build of a heavyweight boxer, struggled on through the US hard-court season during spring but was clearly not fit. In the meantime he had taken on Mats Wilander, a former multi-grand-slam champion, as his coach, although it was not until the French Open that the two were able to spend much time together.

"Mats has been working hard on my concentration levels," said Safin, who, in moments of frustration is well known for smashing his rackets to tiny pieces.

"I've suffered unbelievable ups and downs, sometimes playing great tennis while at other times it seemed I didn't know how to play any more. But I think my consistency is finally improving."

He took the first set easily enough against Johansson, making the game look a breeze, but then his concentration fell away, and it appeared that the Swede might take control.

With the crowd baying for action, Safin was in danger of self-destructing but he tightened his game to the level of the first set to win 6-2, 2-6, 6-4, 7-6.

The moment of truth came midway through the fourth-set tie-break when, with Safin leading 4-2, he drew Johansson into the net with the most deft of drop shots and then won the point with the most delicate of lobs.