In his monthly newsletter, Tiger Woods says:

He's talking about his recent knee surgery, of course. An article in the current Golf World quotes several orthopedic surgeons suggesting that Woods' knee problems will be recurring (but probably manageable) for the rest of his career. And pointed out that this surgery involved the removal of cartilage, a sure sign that the tremendous torque to which Woods subjects his left knee is causing damage, and will continue to do so.

This all impacts my thoughts on a question I've been mulling recently: Who will lose their No. 1 world ranking first - Tiger Woods or Lorena Ochoa?

There have been a lot of articles recently attempting to compare Woods and Ochoa, and their relative dominance of their respective tours. Those kinds of comparisons are very difficult to make, given that the tours are very different (there is much more depth in men's golf than in women's golf, for example).

But Woods and Ochoa are both atop their world rankings by very large margins, and very similar margins, and both the men's and women's world rankings systems are slow to change.

Who will blink first? Woods or Ochoa? Which of the two is likely to slip to No. 2 first?

A few weeks ago I probably would have said Ochoa. She's shown a lot of vulnerability in the past. Granted, she's shown none at all recently, and I suspect she's completely past the final-round meltdowns that cost her some earlier majors. But that vulnerability was there, and who knows - maybe a little bit of it could creep back in under the right (or wrong, I suppose) circumstances.

With Tiger, there's never been that kind of vulnerability; it's hard to imagine there ever could be - at least on the mental side.

I can imagine a handful of players on the LPGA Tour raising their games enough to challenge Lorena directly, even if her game doesn't falter a bit. I can not imagine any golfer on the PGA Tour elevating their game to Woods' level. He will have to fall off some to be caught. (Wait - should I say that? It just now occurs to me that Vijay Singh reached Woods' level - bypassed him - for one year.)

It's a tough question. It's tough to picture either of them falling to No. 2 in the forseeable future.

Except that Ochoa does have one obvious advantage on Woods: She's, what, 7 years younger? Tiger now has a recurring knee problem, and he's creeping into his mid-30s. Can his body hold up to the terrific forces to which he subjects it? Will he have to change his approach, cut back on certain activities, try lower-impact workouts, perhaps even make some swing adjustments at some point to protect the knee?

Woods may start missing time on a semi-regular basis, and when he misses time he'll lose world ranking points. And then, if he falls off just a smidge, well, maybe that will be enough for someone having a career year to jump ahead of him.

That's my quandary in answering the question. Ochoa has shown some fragility, some vulnerability. Has she completely banished those things for the forseeable future? Woods never has -- but is he showing those things now?

Today, at this particular moment, I think Woods will lose the No. 1 ranking before Ochoa does. Ask me tomorrow, maybe I'll have switched back to Ochoa.

What do you think?