Top seeded Grandmaster Veselin Topalov of Bulgaria stormed his way into the quarter-finals with back-to-back victories against GM Zdenko Kozul of Croatia in the World Chess championship in Tripoli, Libya, on Monday.

Second seed GM Michael Adams of England also made it to the quarters following his 1.5-0.5 victory over greenhorn Hakaru Nakamura of the United States.

Rustam Kasmidzhanov of Uzbekistan qualified for the round of eight with his second straight victory over GM Zoltan Almasi of Hungary.

Also making it to the quarters was GM Vladimir Akopian of Armenia, who displayed perfect technique against GM Michal Krasenkow of Poland, winning by a 1.5-0.5 margin.

The lone upset of this round was the ouster of highly regarded GM Alexei Dreev of Russia at the hands of Cuban Lenier Dominiguez.

Having won the first game with black, Topalov was in command right through with his white pieces in the second game against Kozul, who employed the Classical Sicilian to keep himself in with a chance.

Topalov sacrificed a couple of pawns in the middle game to get a better ending and his queen side pawns eventually had the final say.

Adams had little to do with his white pieces, having won the first game with black. Nakamura went for the Alekhine defence and was never really in contention in the 21-move game.

The Englishman went for routine exchanges and when he was enjoying a better position, Nakamura proposed a draw and immediately signed his ouster paper.

Rustam Kasmidzhanov, a finalist at the World Cup in Hyderabad and amongst the 2700 Elo club in 2001, has off late been showing great sparks of coming back into the elite club.

Playing white against Almasi, the Uzbek needed just a draw and following some wild play by the Hungarian in the middle game, won an exchange for little compensation. Almasi resigned after 35 moves after the queens got traded through little combination.

The star performer of the day was Dominiguez, who outplayed Dreev in the first set of tiebreak games played under rapid time control of 25 minutes each with a 10 seconds increment.

Drawing the first game, Dominguez unleashed a fine attack in the second game and won comprehensively to move to the quarters.

Many had believed it to be a good event for Romanian Liviu-Dieter Nisipeanu, the semifinalist of the World championship at Las Vegas in 1999. Especially so as the other two semifinalists in the fray -- Armenian Vladimir Akopian and Adams -- have been going great guns here and have both qualified for the next stage.

However, it was not to be as Nisipeanu lost the battle of nerves against Andrei Kharlov, the only Russian left in the fray apart from third seed Alexander Grishchuk.

After drawing both the games under normal time control, both Kharlov and Nisipeanu won one game each in the rapid, drew both the blitz games that followed before the Romanian ran out of gas in the sudden-death game.

Grishchuk made the grade against veteran Alexander Beliavsky of Slovenia but only after a close battle that was stretched till the blitz games. Grishchuk won the first game of blitz and drew the second after drawing two games in rapid.

Akopian set up his quarterfinal clash with Adams with a fine victory over Krasenkow, who was outplayed in all departments of the game.

The 1999 finalist, Akopian had beaten Adams in the semifinals en-route to his defeat against Russian Alexander Khalifman of Russia in the finals at Las Vegas.

Complete Results, Round 4: Veselin Topalov (Bul) beat Zdenko Kozul (Cro) 2-0; Teimour Radjabov (Aze) beat Pavel Smirnov (Rus) 1-1, 1-1, 1.5-0.5; Michael Adams (Eng) beat Hikaru Nakamura (Usa) 1.5-0.5; Alexander Beliavsky (Slo) lost to Alexander Grishchuk (Rus) 1-1, 1-1, 1.5-0.5; Rustam Kasimdzhanov (Uzb) beat Zoltan Almasi (Hun) 2-0; Vladimir Akopian (Arm) beat Michal Krasenkow (Pol) 1.5-0.5; Lenier Dominiguez (Cub) beat Alexey Dreev (Rus) 1-1, 1.5-0.5; Andrei Kharlov (Rus) beat Liviu-Dieter Nisipeanu (Rom) 1-1, 1-1, 1-1, 1-0.