Monaco descended into crisis on Tuesday as they were knocked out of the Coupe de France last 16 in a 1-0 home defeat by St Etienne -- their third loss under new coach Robert Moreno.
St Etienne prevailed thanks to a first-half goal by Denis Bouanga to leave Monaco out of both domestic cups and with a remote chance of playing in the Champions League next season.
Moreno took over from the sacked Leonardo Jardim during the mid-season break but the new coach has struggled to boost Monaco's confidence despite an encouraging 3-3 draw at Ligue 1 leaders Paris Saint-Germain earlier this month.
The principality side have lost their last two league games, having been beaten 4-1 by PSG at the Parc des Princes and then 3-1 at home by Strasbourg last weekend, leaving them 13th in the standings, eight points off the Champions League spots.
National 2 (fourth-tier) side Belfort earlier knocked out top-flight Montpellier 5-4 on penalties in the biggest upset of the round, while Stade Rennes advanced with a 5-4 win after extra time at Angers in an all-Ligue 1 tie.