Spain's Rafael Nadal returns the ball to Frenchman Gael Monfils (unseen) during their ABN Amro World Tennis Tournament semi-final on February 14, 2009 in Rotterdam. (Rick Nederstigt/AFP/Getty Images)
The Spaniard next plays Britain's Andy Murray, who destroyed Croatian Mario Ancic 6-1 6-2.
Monfils, the only player to beat Nadal this year in the Qatar Open quarter-finals last month, made a poor start by dropping his first service game.
He broke back but then surrendered his serve again in the fifth game.
Nadal, who went to three sets in his previous three matches this week, only needed a single break in the second set to close out Monfils.
Second seed Murray raced through the first set against Ancic in 24 minutes and maintained his rhythm to clinch his second final appearance of the year, after winning in Doha last month.
Murray, though, said an ankle injury would prevent him playing in Marseille next week.
"It felt uncomfortable after yesterday's quarter-final," the Scot told reporters. "I hope it will not be a problem for the final.
"It didn't bother me today as I played really well.
"The physio examined my ankle but could not find any damage. Next week I will try getting my ankle better and prepare for the hardcourt tournaments to come."
