Doyle needed a hernia operation but played on until the last game of the season due to the Sky Blues not being safe from relegation. Now, he has had the operation and surgeons discovered that the extent of the injury was far worse than initailly thought.
Chris Coleman told the CT: "Unfortunately he is going to be out for four months and will miss the start of the season.
"It appears that because he played on it aggravated the injury even more and he has done more damage. He carried on playing to help us out at a difficult time and it is a great shame that he will not be fit for the start of the new campaign."
Meanwhile, the operation on Elliott Ward's ankle was fine and Chris Coleman said: "Elliott is fine and he will be fit for the start of the season."