"I've had physical tests and I'm confident I will come back faster, stronger and fitter than I ever was," Collymore told The Mirror.
The 35-year-old former Liverpool and Aston Villa forward - who flew to Tenerife earlier this week to embark on a three-week fitness programme - estimates that given a month he will be back to his best.
"A month from today, I guarantee I will be able to stand side by side with any striker in the country and my physique will be up there with any of them," Collymore added.
Premiership
Robben slams Chelsea offer
02/08/2007 AT 07:02
"This time I'm not going to self-destruct. You are not going to see headlines about me being kicked out of a bar somewhere in the early hours rolling drunk.
"l know I can still be among the best."
Premiership
Euroscout - Kevin Prince Boateng
01/08/2007 AT 19:34
Premiership
Hammers agree Dyer fee
01/08/2007 AT 19:04