TORONTO – Not everybody believes Pedro Martinez’ hip is the reason he may not start tomorrow night against the Yankees.

“[Boston] is saying it’s his hip, but it could be his shoulder,” an AL source told The Post yesterday.

Officially, the Red Sox are saying Martinez is suffering from a left hip strain. In his last start against the Yankees at Fenway Park Wednesday, Martinez’ fastball topped out at only 92 mph as he threw 117 pitches and absorbed a 7-0 loss.

With the Red Sox having virtually no chance of catching the Yankees in the AL East, where they are 7 ½ games out and their wild-card hopes quickly sliding away, Boston may not want to take a chance with Martinez no matter what his ailment is.

Martinez, who is 17-4 with a major league-best 2.22 ERA, wasn’t with the Red Sox for the weekend series in Cleveland. Instead, he was in Boston receiving treatment. He was expected to meet his mates last night when the club arrived in New York. The decision whether to start Martinez or Frank Castillo will be made today.

When it comes to Castillo and the Yankees, the Bombers don’t catch much of a break because he is 3-0 with a 2.41 career ERA against them.