MONTE CARLO, April 21: Roger Federer and Rafael Nadal eased into the Monte Carlo Masters quarterfinals on Thursday with efficient straight-set wins.

Top seed Federer added more polish to his own clay game as he knocked out local hero Benjamin Balleret, a 23-year-old from the tiny principality, 6-3, 6-2.

Spain's Nadal, the defending champion and the only man to have beaten Federer this year, imposed himself with a 6-3, 6-3 defeat of Belgian Kristof Vliegen.

Nadal, winner of 11 titles last season - including eight on clay highlighted by his French Open triumph - continued to improve as he plays on the surface for the first time this season.

“I played better today than in my other matches,” said the smiling second seed, who went for a practise session after his victory.

“I improved my forehand and my serve - maybe my backhand. I ran a lot, I'm glad to raise my level. Now that I'm into the quarterfinals I can enjoy the tournament.”

Nadal now faces a re-run of last year's final as he takes on Argentine sixth seed Guillermo Coria, who beat Germany's Nicolas Kiefer 6-7 (5-7), 6-4, 6-3.

Coria continued to struggle on serve, striking a massive 23 double-faults.

Federer paid tribute to Balleret who refused to be cowed by the Swiss superstar.

“I thought he played very well for one and a half sets until he played a couple of loose games, which I took advantage of it,” said Federer.

“But for one and a half sets, it was a tough match and I really had to play good tennis.

“I'm happy the way I played and the way I handled the situation because it wasn't easy,” he said after beating the number 352 outsider.

Federer now takes on Spain's David Ferrer for a place in the last four.

If he comes through that, he could take on Croatia's Ivan Ljubicic, the fourth seed, who reached the last eight by eliminating the last Frenchman in the field, Gilles Simon 6-3, 6-2.

With one more another pair of victories on Friday, Federer and Ljubicic will line up for a third time this season.

The Swiss owns both of their previous meetings, which he won at the Miami final three weeks ago and the Indian Wells quarters.

Federer's victory ran his personal win streak in Masters

Series tournaments to a record 27-straight.

Ljubicic faces either Chile's Fernando Gonzalez or Robin Soderling of Sweden for a place in the semifinals.

Ljubicic stands second behind Federer in match wins this season with a 29-4 record.

In a Spanish clay showdown, eighth seed Ferrer sent two-time tournament champion Juan Carlos Ferrero deeper into crisis 6-1, 6-7 (5-7), 6-3 to reach the last eight.

Ferrero, a former world number one, lost in the first round last week in Valencia, on home ground.

Ferrer proved difficult to stop on hardcourt last month in Miami as he upset Andy Roddick before losing to Federer in the semifinals.

Spain's 15th seed Tommy Robredo upset third seed David Nalbandian 5-7, 6-1, 7-5 to reach the quarterfinals.

Thursday’s results:

Third round: 12-Fernando Gonzalez (Chile) bt Robin Soederling (Sweden) 6-2, 3-1 – Soderling retired; 6-Guillermo Coria (Argentina) bt 9-Nicolas Kiefer (Germany) 6-7 (5-7), 6-4, 6-3; 2-Rafael Nadal (Spain) bt Kristof Vliegen (Belgium) 6-3, 6-3; 7-Gaston Gaudio (Argentina) bt Alessio Di Mauro (Italy) 6-2, 6-4; 1-Roger Federer (Switzerland) bt Benjamin Balleret (Monaco) 6-3, 6-2; 15-Tommy Robredo (Spain) bt 3-David Nalbandian (Argentina) 5-7, 6-1, 7-5; 4-Ivan Ljubicic (Croatia) bt Gilles Simon (France) 6-3, 6-2; 8-David Ferrer (Spain) bt 11-Juan Carlos Ferrero (Spain) 6-1, 6-7 (5-7), 6-3.—Agencies