An under-strength Siena stunned Napoli 2-1 today to take a decisive step towards a first ever Italian Cup final. Brazilian Reginaldo and Gaetano D\'Agostino scored the goals to give Siena a semi-final, first leg victory, although they may live to rue Emanuele Pesoli\'s late own-goal. Napoli may still be favourites to progress ahead of next month\'s second leg in Naples, but Siena can be well pleased with their night\'s work. The visitors played a full-strength side while the Serie A strugglers rested several first-choice players.  And yet they had more determination and cohesion as they put one foot in the final and a possible glamour tie against one of the country\'s heavyweights. Juventus won by the same score away to AC Milan in the first semi-final, first leg on Wednesday.