Monaco splashed out over €150 million (£130m) on transfers including € 64 million (£55m) on Colombia striker Falcao, who cleverly poked the ball home five minutes after Emmanuel Riviere had opened the scoring in the 82nd minute.
After talismanic striker Lisandro Lopez had bid farewell to fans and team mates, Alexandre Lacazette netted a double to give Olympique Lyonnais a 4-0 home win against Nice.
Lisandro is joining Qatar club Al Gharafa after four years at Lyon, but Lacazette showed he was willing to make sure the Argentine would be quickly forgotten by putting his side on top of the standings with goals either side of the break.
After four years in Ligue 2, Nantes beat Bastia 2-0 at home.
Centre back Uros Spajic, who joined Toulouse from Red Star Belgrade, experienced a Kafkaesque Ligue 1 debut when he was sent off for a foul in the box that was clearly committed by team mate Steeve Yago in a 3-0 defeat at Valenciennes.
On Friday, champions Paris St Germain failed to shine in a1-1 draw at Montpellier with Zlatan Ibrahimovic and Edinson Cavani, who form one of the most formidable strike pairings in Europe, unable to find the back of the net