Djokovic dropped serve twice in the first set and once in each the second and third sets. However, he ended up with seven breaks of his own, with three in both the final two sets.
Eight-time tournament defending champion Rafael Nadal continued his 2013 roll, and stopped No. 16-seeded Philipp Kohlschreiber 6-2, 6-4 without facing a break point. Nadal, who has won 44 consecutive matches at the Monte Carlo Masters, improved to 19-1 in 2013 as he seeks his fourth tournament title of the year.
But second-ranked Andy Murray was routed by 13th-seeded Stanislas Wawrinka 6-1, 6-2 in less than an hour. Wawrinka lost only 10 points in seven games on serve while winning 55 percent of the points off Murray's serve.
Also Thursday, No. 6-seeded Jo-Wilfried Tsonga raced past Jurgen Melzer; seventh-seeded Richard Gasquet beat ninth-seeded Marin Cilic 7-5, 6-4; and Grigor Dimitrov advanced 6-2, 6-4 over Florian Mayer.
Friday's quarterfinals have Djokovic playing Nieminen and Gasquet meeting Fognini in one half the draw. Nadal goes against Dimitrov and Tsonga faces Wawrinka in the other.