Injury-hit AC Milan were plunged further into crisis by a surprise 1-0 defeat at home to Sampdoria in Serie A on Sunday.
Luis Muriel's 69th-minute penalty was enough to consign Milan to their fourth successive defeat in all competitions.
Milan were third in December but one point from their past four league matches has seen them slip to eighth, 10 points behind the Champions League places.
They are 14 points behind league leaders Juventus, who hosts Inter Milan in the Derby d'Italia later.
The Rossoneri lost Giacomo Bonaventura, Mattia De Sciglio and Luca Antonelli to injury last week.
After a balanced first half, Milan should have taken the lead immediately after the break. Emiliano Viviano could only parry Suso's cross-shot but Gerard Deulofeu, who was making his first start, struck the rebound onto the post from a good position.
Milan had further chances to take the lead before Sampdoria broke the deadlock after Gabriel Paletta tripped Fabio Quagliarella in the area and Muriel fired the resulting spot kick into the bottom right corner.
Filip Djuricic almost doubled Samp's lead but shot inches wide.
Milan should have levelled three minutes from time but Gianluca Lapadula fired straight at Viviano from close range and two follow-up efforts were blocked before the ball was finally cleared.
Milan's misery was compounded in the final minute when Jose Sosa was sent off following two yellow cards in five minutes.