Dimitar Berbatov scored his first Monaco goal to carry Claudio Ranieri's team through to the quarter-finals of the Coupe de France at the expense of Nice.
The Bulgarian was a deadline-day addition from Fulham and made his debut in Sunday's Ligue 1 draw with Paris Saint-Germain.
Introduced midway through the second half in the cup game against Monaco's south-coast neighbours Nice, who had Timothee Kolodziejczak sent off in the 48th minute, Berbatov ended the home side's resistance in extra time, netting after 113 minutes to earn a 1-0 win.
Guingamp ended L'Ile de Rousse's campaign, winning 2-0 against the minnows from amateur league CFA 2 who had knocked out Bordeaux on penalties in the previous round.
Gregory Cerdan netted a 39th-minute opener for visitors Guingamp, before Moustapha Diallo put the seal on the win by scoring the second goal after 57 minutes.
AS Moulins live on in the cup, the CFA team winning 3-1 at home against CFA 2 outfit Sete with two goals from Sebastien Da Silva and a Xavier Burdin own goal.
Sete had taken an early lead through Christophe Rouve, but he was also sent off as the match began to slip away, with team-mate Kaoussou Diakhate also dismissed in the late stages.
Ligue 1 Rennes joined the last-eight line-up after winning 1-0 at second-tier Auxerre, with Foued Kadir netting the only goal in the 24th minute. Auxerre's prospects were hurt by Yann Boe-Kane's red card in the 56th minute.