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World No. 1 and two-time Miami champion Roger Federer refused another fourth round upset at the hands of an Argentine, defeating Jose Acasuso 7-6(5), 6-2 on Tuesday in Miami to book his place in the Sony Ericsson Open quarterfinals.

He will next face 2004 titlist Andy Roddick, a 4-6, 6-3, 6-2 winner over Frenchman Julien Benneteau in the night session. With Roddick's victory, it is the first time since 1987 in Miami that six of the Top 10 seeds have reached the quarterfinals and only the third time (1986) in the tournament's 24-year history.

In Federer's match, Acasuso saved all four break point chances he faced in the opening set to force a tie-break, but could not hold off the Swiss in the decider. With the set lead secured, Federer raced out to a 4-0 advantage in the second set and proceeded to close out the match on serve in one hour and 14 minutes.

"It was key for me to serve well, especially in the beginning, and it was a good serving day today," said Federer, who fired 12 aces en route to his 30th career match win in Miami. "I was very happy with it."

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Federer won the Miami title in 2005-06, but was edged out in a third set tie-break by Argentine Guillermo Canas last year in the fourth round. Last week in Indian Wells, he came up just shy of his first final of the 2008 season when he lost to American Mardy Fish in the semifinals.

"Now I feel like I'm playing well," he said. "You can tell, as well, I'm moving well and playing well and serving well. That's what it comes down to for me.

"All these matches are a grind. If you look back you always probably thought I won every match 6-2, 6-3. It wasn't like that. I had many matches I came through in a close way, and that's what made me the best player for so long, is winning those big points over and over again."

Roddick shook off a sluggish start against the unseeded Benneteau to advance to the Miami quarterfinals for the fifth time, also his third year in a row.

"I just didn't feel clean in the beginning," said the World No. 6. "I guess over the years I've become pretty good at trying to figure out a way to win matches when I don't feel like I'm hitting it that great, and tonight was one of those. But after the rain delay I felt I hit it about as well as I hit in this tournament so far."

The American takes a 1-15 lifetime record into his match against Federer, his only win coming in 2003 in a third set tie-break in the Rogers Masters semifinals. Roddick said: "He's one of the few guys that I've probably played three or four really, really good matches against him and came up short. I think I have brought out the best in him a couple of times.

"All I can do is put my best foot forward, and hopefully right now he's thinking about it a little bit. You know, obviously I think I have to serve well. Just goes down to the basics: You serve well, you return well, you're going to give yourself looks against anybody."

Unseeded Serb Janko Tisparevic once again held Russian Mikhail Youzhny's number, upsetting the No. 11 seed 3-6, 6-0, 6-3 as he converted on five of his 12 break point chances. The 23-year-old Tipsarevic had also defeated Youzhny in their first career meeting, February at Rotterdam.

Tipsarevic, who reached a career-high No. 40 in the South African Airways ATP Rankings last month, is playing in just his seventh ATP Masters Series tournament. His previous best result was a third round finish last year in Indian Wells.

The Serb No. 2 will be making his second quarterfinal appearance this year after Zagreb, where he lost to eventual champion Sergiy Stakhovsky. At the Australian Open, Tipsarevic took Federer to a 10-8 fifth set in the third round.

Tipsarevic next faces another Russian, World No. 4 Nikolay Davydenko, who toughed out a 4-6, 6-3, 7-5 win over Croatian wild card Mario Ancic in two hours and 29 minutes. Davydenko defeated the Serb last year in the Moscow semifinals en route to his 11th career ATP title.

Davydenko advances to the Miami quarterfinals for the first time in seven event appearances, and will be attempting to reach the semifinals for the third time this year.

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Monday: Roddick, Youzhny Advance to Last 16
Monday: Federer Joins Davydenko in Fourth Round
Sunday: Nadal Returns to 4th Rd.; Canas, Mathieu, Andreev Advance
Sunday: Blake Outlasts Santoro; Berdych Advances Easily
Saturday: Federer, Roddick Win Openers; Murray, Hewitt Fall
Saturday: Tsonga Wins in Miami Debut; Seed Exodus Continues
Friday: Qualifier Anderson Upsets Defending Champ Djokovic
Friday: Nadal Advances to Third Round
Thursday: Monfils Rallies to Defeat Isner
Thursday: Reynolds Upsets Safin; Russian Struggles Continue
Wednesday: Querrey Advances Along With Teenagers Cilic, del Potro
Wednesday: Fans Favorite Kuerten Falls in Opener