Guingamp substitute Fatih Atik and Mustapha Yatabare netted in the 112nd and 117th minutes respectively to set up a Brittany final against Stade Rennes, who beat Ligue 2 Angers 3-2 on Tuesday, at the Stade de France on May 3.
Monaco, who spent over 100 million euros ($138 million) on players during the close season, are out of the League Cup and lie second in Ligue 1, 10 points behind leaders Paris St Germain with five games left.
Monaco, however, dominated and were rewarded nine minutes from time when Bulgarian striker Dimitar Berbatov equalised by tapping in Fabinho's pass back.
Guingamp were the better side in the second half, going very close several times through Yatabare, but no goals were scored and the tie went into extra time.
Atik put Guingamp ahead with a nice volley from Thibault Giresse's cross.
Giresse, the son of former France midfielder Alain Giresse, also set up Yatabare just inside the box and the Mali striker put the result beyond doubt. ($1 = 0.7243 Euros)
- Sports & Recreation
- Stade de France
- Stade Rennes