KANSAS CITY – If you are a Yankee, the only thing you have to hang hope on concerning Mariano Rivera’s bothersome right forearm are the following words: “The MRI showed no structural damage.”

In other words, no bone chips were found in the elbow. No ligaments or tendons were torn.

Yet in the week since Rivera underwent the MRI exam, the closer has played one game of light catch and doesn’t know when he will return to the Yankees’ bullpen.

Though the Yankees downplay the severity of the problem, it’s an arm, and it’s the right one hanging from Rivera’s shoulder. Enough said.

“I will play catch again Friday,” Rivera said after Tuesday night’s 5-0 loss to the Royals.

Because he tossed lightly with pitching coach Ron Guidry on Monday afternoon, it was assumed Rivera would at least repeat that exercise yesterday. But after Monday’s session, Rivera said the forearm “felt tight.”

He didn’t pick up a ball Tuesday and didn’t plan on doing anything yesterday. Today is a day off, so the earliest he would throw again would be tomorrow.

Considering Rivera said he needs to throw off a bullpen mound before he is ready for a game, it’s likely he won’t be available for any of the four games in Baltimore that start tomorrow.

So, is it time to be concerned?

“Not at this point,” Brian Cashman said. “I only get concerned if I am told to be concerned.”

Having a large lead over the Red Sox in the AL East (eight at the start of last night’s action) helps ease the stress of not having Rivera.

Since Thursday, when Rivera posted his 33rd save hours after getting out of the MRI tube, the Yankees played five games without a save situation presenting itself for Kyle Farnsworth, who is in Rivera’s role.

As long as the lead over the Red Sox remains fat, the Yankees can give Rivera all the time he needs. But if the lead shrinks, Rivera’s absence will be felt.

And what about October? On one hand, it’s good Rivera can rest, but how long before rust builds? Or even worse: The arm is still an issue when the playoffs begin.