Cricketers risk making a fool of themselves if they try to deceive technology by challenging close dismissals even when they know they are out under the Decision Review System, England batsman Alastair Cook has warned.

In the ongoing fifth Ashes Test against Australia, visiting batsman Ian Bell challenged the umpire's decision after being adjudged out caught behind and had the decision overturned in his favour through a controversial referral which could not provide any conclusive evidence for or against the on-field official's verdict.