MONTE CARLO (AFP) - Triple champion Rafael Nadal and world number one Roger Federer remained on course for another installment in their epic rivalry by moving into the Monte Carlo Masters semi-finals on Friday.

Top seed Federer fought back from a brutal first set assault to beat Argentine sixth seed David Nalbandian 5-7, 6-2, 6-2.

Federer, the runner-up to Nadal for the past two years, goes on to face either third seed Novak Djokovic of Serbia or America's Sam Querrey for a place in Sunday's final.

Nadal, who is hoping to be the first man since 1914 to win four Monte Carlo titles in a row, saw off fifth-seeded Spanish compatriot David Ferrer 6-1, 7-5 and will tackle fourth seed Nikolay Davydenko of Russia.

Nadal took his Monte Carlo record to 22 wins in 23 matches and has now won 96 of his last 97 claycourt ties.

Federer admitted he was happy to be in the semi-finals after a trying year which has seen him suffer from glandular fever and lose his Australian Open title.

"This was my best match of the tournament. I was happy with my movement and the level of play was excellent," said Federer after his ninth win in 17 career meetings with the muscular Nalbandian.

"I could have served a little better but the statistics were good. David's a great player and a wonderful ball-striker. He has great movement and anticipation.

"It's always nice to play him. You know he's not going to hand it over to you. He's won on clay this year and has played Davis Cup on the surface so to beat him is a big satisfaction."

Nalbandian, consistently finding the angles, broke to lead 6-5 in the opener which he converted into a one-set advantage on a third set point when Federer hit a backhand wide.

Federer, who was two points away from defeat in his opening match with Spain's world 137 Ruben Ramirez Hidalgo, nipped ahead to lead 4-2 in the second set and held on to back it up to go 5-2.

He broke the Argentinian for the third time to level the quarter-final when Nalbandian went long with a tame forehand.

Federer piled on the pressure in the decider and broke to lead 4-2 when his tiring opponent netted an awkward volley from a return which landed at his toes.

Another supremely confident service game followed to put the top seed ahead at 5-2.

Victory arrived in the next game on his first match point courtesy of a swooping crosscourt forehand winner with Federer reaping the reward for a daring fightback which saw him hit 43 ambitious winners to Nalbandian's 27.

"I think today he was playing at high level and it could have been one of his best matches on a clay court," said Nalbandian.

Nadal raced through the first set against Ferrer on the back of three lightning breaks of serve before facing a determined counter-attack.

The 26-year-old, fresh from his Valencia title last weekend, stormed into a 3-0 lead in the second set before Nadal claimed one break back.

Ferrer then squandered three set points in the 10th game as Nadal levelled at 5-5 and then wasted two break points to allow his younger compatriot to sneak 6-5 ahead.

He didn't get another chance as Nadal took victory on his first match point with a trademark running forehand.

Russian fourth seed Nikolay Davydenko reached his fifth semi-final of 2008 with a gruelling 6-3, 4-6, 7-5 victory over Davis Cup teammate Igor Andreev in a match which saw 16 breaks of serve.

The 2hr 45min marathon also witnessed Davydenko sending down an ugly 61 unforced errors.