West Bromwich Albion proved too strong for Derby County with a 2-0 away win in a pre-season friendly at Pride Park.
Playing their final game of pre-season ahead of the start of the new Championship campaign, Derby slipped up against their Premier league opponents.
Graham Dorrans and Markus Rosenberg were both on the scoresheet for the Baggies as they cruised to victory.
Dorrans stole the show with a stunning 25-yard strike just before half-time before Jamie Ward forced visiting keeper Ben Foster into a smart save.
Will Hughes had the Rams' best chance after the restart but Rosenberg sealed the win when he struck in the final minute.
The Spireites who took the lead after 29 minutes through trialist Hamza Bencherif, who rose highest to head a Gary Roberts cross beyond Chris Kirkland.
Drew Talbot missed a great chance to double the advantage early in the second half when he had time to compose himself but could only fire wide.
Chesterfield were made to pay for their wastefulness late on when Maguire unleashed a spectacular 20-yard strike that beat Tommy Lee and bounced in off the right-hand post.