Kristian Dennis scored his third goal of the season as Chesterfield beat Port Vale 2-0 to climb off the bottom of League Two.Dennis and midfielder Jordan Sinnott struck in the space of five first-half minutes to give Chesterfield their first victory of the season and condemn Vale to a second consecutive defeat.Vale had been the better side until Chesterfield manager Gary Caldwell brought an extra man into midfield and the decision paid off when Sinnott played in Dennis, who scored with a low shot from 12 yards in the 39th minute.Sinnott struck the bar before beating Sam Hornby from 15 yards in the 43rd minute to completely transform the game and Chesterfield remained on top in the second half.Vale substitute Anthony de Freitas flashed a shot just wide in the 75th minute, Marcus Harness was also off target in the 82nd minute and Tom Pope had a header saved on the line by Tommy Lee, playing his first game for more than a year.