Monaco knocks off Ajaccio
Missing Colombia striker Radamel Falcao through injury, Monaco needed to work hard to convert its domination into a goal.
Valere Germain missed an easy tap-in from a low cross by Layvin Kurzawa in the 75th minute, but Andrea Raggi at the far post prevented the ball from running out of bounds and cut it back for Riviere, who scored from close range.
Also Sunday, 10-man Bordeaux earned a third straight win by defeating Lille 1-0 to get back in the race for a European spot, while mid-table Lyon beat Bastia 3-1 and Toulouse drew 1-1 with Montpellier.
''It was important to take advantage of Lille's slip,'' Monaco defender Eric Abidal said. ''It was not a pretty match, but like the coach sometimes says, no matter how you play, the most important thing is to win.''
Monaco forward Anthony Martial, one of the most promising prospects in the league at 18, took a pass from James Rodriguez in the 16th and dribbled past three defenders to fire a low strike that Ajaccio goalkeeper Guillermo Ochoa palmed away.
Ochoa frustrated Monaco by tipping a powerful drive from Jeremy Toulalan over the bar in the 20th and saving a header from Ricardo Carvalho in the 56th from a corner.
Ajaccio was reduced to 10 men in the 62nd when Jean-Baptiste Pierazzi picked up a second yellow card for tripping Rodriguez.
Monaco capitalized on its numerical superiority to take the lead before striking the post twice with free kicks from Rodriguez in the 80th and playmaker Joao Moutinho in the 84th.