!999 Mazda Protege cranks but won't start

My vehicle stopped running while driving down the highway. It will crank over but will not start. It has over 100,000 miles. I can hear the fuel pump running, I checked for spark and it is working. I pulled the spark plug and have pressure in the cylinder (2 checked)Could the timing belt have slipped slightly amd I still get all of the above?
Thanks,