Because he is who he is — and what he is — the one thing certain about Mark Messier's stubborn left shoulder injury was that he would be the last to give in to it.

He still hasn't, but he at least knows it might be a possibility — that he might have to undergo arthroscopic surgery that would at least end his regular season.

The Rangers' captain subjected himself to a cutting-edge form of treatment over the Olympic break that was his last, best hope to avoid surgery. At a clinic in Toronto, Messier had electroshock waves delivered into his strained and inflamed left rotator cuff via a Sonorex machine.

The treatment, like a deep-muscle massage, can be painful in its immediate aftermath. So Messier's inability to immediately resume practice with the Rangers Thursday isn't indicative of much.

Rather, the Rangers' medical staff, which acknowledged a month ago that surgery was a possibility, has advised Messier to rest and continue rehab therapy for the next several days.

At some point next week, after assessing Messier's progress and pain level, team orthopedists Andrew Feldman and Tony Maddalo will get together with Messier and GM Glen Sather and make a decision about the 41-year-old's immediate future.

Surgery would at least end Messier's regular season. And for him to return, the Rangers would probably have to advance past the first round of the playoffs.

"We're still talking about it; we haven't come to a conclusion yet," Sather said yesterday in Salt Lake City, where he'll remain to accompany home the five Rangers in the Olympic tournament.

Of the treatment, Sather said: "It helped him a little, but I don't think it helped him enough."