The Dons were beaten 4-2 on Saturday after leading 2-0 at half-time and Cash said his side must improve before the competitive opener against Stevenage in the Capital One Cup in just over a week's time.

"We created six or seven good opportunities against a decent team in the first half but our goalkeeper also had to make three good saves," Cash told the club's official website.

"It was a very open game and was pleasing on the eye but in the second half we just collapsed and we cannot afford to defend like that again. There were too many defensive mistakes.

"Pre-season is all about learning from the mistakes you make in games and we have to improve on the performance that we gave. The players had a bit of a dressing down afterwards. We will look at it on the DVD and work on the things that we did wrong in training.

"It is not just the defence as defending starts from the front. It has been one of our worst pre-seasons in terms of results and we have to aim to improve against Portsmouth on Wednesday and take that into the Stevenage tie."