Double whammy for Cook
Paul Cook had to deal with Chesterfield's FA Cup exit after a 3-1 loss to Southend and seeing Gary Roberts forced off with injury.
Chesterfield scored in the fouth minute when Roberts crossed low to the far post, where Tendayi Darikwa fired past Southend keeper Dan Bentley, but the visitors equalised eight minutes later when Marc Laird headed in Ben Coker's corner.
The home side were behind 60 seconds later when ex-Chesterfield forward Kevan Hurst crossed from the right for Anthony Straker to plant a back post header past Chesterfield keeper Tommy Lee.
Roberts was forced off in the 16th minute with a hamstring problem.
Drew Talbot headed against the top of the Southend crossbar in the 52nd minute, but the visitors had a great chance to settle it in the 79th minute.
Sam Hird barged over Barry Corr to concede a penalty, but the striker's spot kick was superbly saved by Lee only for Hurst to finish it in the 85th minute from 12 yards after great work by Straker.
Cook said: "It's very disappointing after getting such a great start and you expect to go on and show confidence and do all the things we didn't do.
"We allowed Southend to start dominating possession and they got two very quick goals which gave them confidence and although we were slightly the better team in the second half, it was too little too late.
"Everyone is disappointed because everyone wants a cup run and be in that third round, but you must take disappointing days on the chin and be a man."
On Roberts' injury, Cook added: "I think he's done a hamstring. The prognosis for that is normally six weeks, so that's a very disappointing blow."