Sampdoria's winless run stretched to seven matches after a goalless draw at home to Atalanta.The visitors made the brighter start and former Italy forward Alessandro Diamanti fired an early effort over the crossbar, before Mauricio Pinilla headed narrowly wide.Sampdoria's first decent chance arrived just before half-time but Fabio Quagliarella drove his shot too high.The hosts almost took the lead shortly after the break but Dodo's header from Mattia Cassani's cross was well saved by Marco Sportiello.Andrea Ranocchia had a late chance to win it for Samp but skewed his shot high and wide.