The Crawley Observer had been told he was injured and last week assistant Warren Feeney said there was a chance he may make the squad for the Wycombe trip. But he was not in the squad for that game (he was at Leyton Orient's match) or Tuesday night's match.
However fans have been suggesting on social media he is out of favour. And a Twitter account called @Whereiscox has been set up. It's profile says, 'On a mission to find Dean Cox- If you have any information then please contact me or @HarryKewell'
When asked on Tuesday, 'where is Dean Cox?', Kewell responded: "Good question, where is he?
"You can ask all my players, as long as you work hard, you will always have an opportunity here. I have showed that to some players who have been left out of the squad and they have come in and taken their chance.
"All my players will always have a chance of playing they have got to work hard at training have the right attitude and when they do that everyone has a chance to play."
The 29-year-old attacking midfielder has been a fans' favourite ever since signed a two-and-a-half-year contract after he left Leyton Orient by mutual consent in September 2016.
Cox has made four appearances this season.