Luigi Del Neri remains winless since taking charge of Genoa as struggling Siena inflicted a fourth straight defeat on the Rossoblu with a 1-0 victory at the Stadio Artemio Franchi.
Massimo Paci's goal early in the second half gained the Tuscan side only their second win of the season, the first coming against Bologna at the end of September, and lifted them to within three points of their opponents, who occupy the first position above the relegation zone.
It was also a personal satisfaction for Siena coach Serse Cosmi, who led Genoa to the Serie B title in 2005, but left following their imposed relegation to Serie C due to financial malpractice.
Both sides came into the game struggling at the wrong end of Serie A and the nerves led to an inevitably tight game.
Chances were few and far between with neither side wanting to take a risk, but a long ball from Matteo Contini provided the home team with their first chance of the game in the 12th minute, and one they should probably have done more with.
Emanuele Calaio beat the offside trap and escaped the attention of Cesare Bovo, leaving him with just Sebastien Frey to beat, but the French goalkeeper stood up to him and made the save.
Genoa were unable to create any chances from open play, but a free-kick provided Bosko Jankovic with the chance to put them ahead in the 24th minute.
He only just missed the target by a matter of inches from over 25 yards out.
Another effort from long distance, this time from Andrea Bertolacci, also only just missed the post with Gianluca Pegolo getting the slightest touches to the ball on its way wide.
Paci gave Siena the lead in the 55th minute with Paci meeting Francesco Valiani's corner at the near post and heading the ball past Frey.
Del Neri responded by sending on two young attackers, Ahmed Said and Giammario Piscitella, putting a huge weight of responsibility on their inexperienced shoulders.
Said almost scored in the 70th minute, but Pegolo got to the ball first to divert Luca Antonelli's low cross away.
Siena packed men in behind the ball, making life difficult for Genoa, who were unable to find a way through.
For the third time in a row after replacing Luigi De Canio, Del Neri found himself on the losing side with a lot of work to be done to lift the Rossoblu away from danger at the bottom of Serie A.