The Valiants fell to a narrow defeat in their first pre-season friendly at Vale Park on Tuesday night as Derby County edged a well contested game.
Michael Tonge, Rekeil Pyke and Billy Reeves all went close for Vale, but a Darren Bent penalty separated the two sides on the scoreboard.
In the opening five minutes both sides jostled for possession, but it was Vale who looked the more threatening as Tom Pope saw a deflected header fizz wide of the target following a Cristian Montano cross.
With seven minutes on the clock Derby created a shooting opportunity of their own, but Craig Bryson could only curl wide of Sam Hornby’s post.
Up the other end just moments later, Michael Tonge fired a distant effort towards the top corner but Scott Carson reacted well to deny him.
Derby came close to opening the scoring on 23 minutes as Johnny Russell latched onto a Curtis Davies long ball before looping a strike over the bar.
A similar opportunity was then wasted by the visitors five minutes later as Darren Bent blazed one way off target from close range.
Bent than had another chance fall his way with 41 minutes played but Hornby got across to make the save.
The next attack then lead to Vale getting a shot away themselves but Dan Turner could only drill one wide after a neat turn on the edge of the box.
Following the restart, Vale looked the brighter of the two teams early on and Joe Davis called Carson into action on 48 minutes.
However, it was the visitors who took the lead from the spot three minutes later after a questionable penalty decision went against Montano. Bent was the player who then stepped up to convert the spot-kick despite the best efforts of Hornby.
Michael Brown then made a host of changes just after the hour mark, but the Valiants continued to match Derby and keep the ball well.
Rekeil Pyke almost levelled the scores on 68 minutes as he diverted a Tyrone Barnett knock-down towards goal. Carson did well to save, however, and the goalkeeper was required again seconds later as he thwarted Billy Reeves from six yards.
Brilliant footwork from Turner caused panic in the Derby area on 74 minutes, but the young Vale striker couldn’t find Pyke and the away side managed to clear.
Reeves then found the gloves of Carson soon after Pugh found him with a pinpoint pass. Substitute Ryan Boot made a save of his own in the home goal on 80 minutes as he safely held a Ikechi Anya strike.
Despite the pressure that Vale put on the Rams, Carson remained unbeaten come the final whistle and it meant that the Valiants suffered their first defeat of pre-season.
Importantly, however, the players put in a strong performance and got vital minutes into their legs as the preparations continue ahead of the 2017/18 season.
Port Vale: Hornby (Boot 60), Wilson © (Kay 45), Eardley (Yates 76), Davis (Smith 62), Gunning (Kelly 76), Tonge (Pugh 62), Harness, de Freitas (Calveley 62), Pope (Pyke 62), Turner (Barnett 62), Montano (Reeves 62).
Derby County: Carson, Wisdom, Baird, Davies, Olsson, Huddlestone (Stabana 66), Bryson, Elsnik, Russell, Anya, Bent (Zanzala 54).
Unused Substitutes: Ravas, Wassall, MacDonald, Walker, Thomas, Bateman, Cover.