No, Mariano Rivera will not be back this season.

Brian Cashman has said it repeatedly and emphatically since the closer tore his ACL in Kansas City on May 3. Joe Girardi, who has an aversion to speaking in absolutes, put it at "99.9" percent.

Still, the 42-year-old Rivera is healing well. He threw his first flat-ground session of his rehab, watched by pitching coach Larry Rothschild, in the outfield 3½ hours before Monday night's game.

Rivera declined to speak with reporters during batting practice, but when asked at the end of BP how he is doing, he responded, "I'm good.''

"I didn't have a chance to see it. Larry told me he threw well and looked pretty good," Girardi said. "When you're a baseball player and you can't do the things you're used to doing, as soon as you can do it, you try."

As for a 2012 return, after giving a cryptic "the only thing I'm certain of is we're all going to die," Girardi settled on this:

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"I don't see it happening."

Chavez back

Eric Chavez, who experienced some soreness in his back after playing four straight games in Detroit last week, started at third and hit fifth Monday night.

"I'm going to check with him, every day, how he's doing," Girardi said. "We have an open communication . . . The thing is, this week we're going to see some lefties [starters], so we're not going to have to worry about the days in a row."

Girardi had planned to give Chavez the weekend off in Toronto anyway but said he would have used the veteran only in an emergency because of the back soreness.

A-Rod swinging

Alex Rodriguez (left fifth metacarpal fracture) took about 40 tee-and-toss swings with his top hand in the indoor batting cage before the game, which he's been doing for the better part of a week. "It has more to do with just keeping his swing in rhythm when he comes back," hitting coach Kevin Long said. A-Rod, expected back by mid-September, is scheduled to have his weekly X-ray Tuesday night.