By Jon Wertheim

How come you hardly ever talk about or investigate tennis players and doping? We only hear about positive tests when [the ITF] publicize the results. But you hardly ever comment on players that are suddenly looking different, suddenly hitting the ball harder, etc. This is talked about [on one website in particular] but journalists should investigate this! --Ben P., New York

• A variation of this question has been posed at least a dozen times since the U.S. Open. This is an issue that vexes journalists and media types all the time. We make a lot of the same observations that you do. We share some of the skepticism. We receive tips -- often vague and anonymous, but tips nonetheless -- about suspicious behavior. The question, however, becomes "then what?" It's easy to speculate or to traffic in rumor. It's hard to accumulate the proof that meets any sort of journalistic threshold. Testing is usually confidential. Few with knowledge have a motivation to speak. If you're willing to cheat by doping, you're willing to lie when asked directly. (Especially when there's no subpoena power.)

I recently watched The Tenth Inning, the latest installment of the Ken Burns baseball documentary. It pertained largely to the "steroid era," that 1994-2000 period when records were obliterated and "Chicks dig the long ball" was the prevailing ethos. There was a collective sense of, "We should have suspected something wasn't right." Truth is, many did suspect just that. But short of evidence, it's hard to start fingering suspects. Ironically, the case was "cracked" not by a positive test but when Mark McGwire left Andro in plain view in his clubhouse stall. Think about the subsequent "busts." The BALCO scandal entailed some terrific reporting, but was essential a fluke, resting as it did on leaked grand jury testimony. The Mitchell Report rested largely on "non-analytic" evidence. There was evidence that athletes received drugs via online pharmacies and clubhouse attendants, but the actual positive test results were few and far between. The Capitol Hill debacle came about mostly because there was a perjury penalty hovering.

None of this is to give the media a pass, nor to suggest that there aren't creative ways to investigate and advance the story. But the difference between suspicion and a provable, printable allegation isn't a gap; it's a canyon.

As for tennis, I stand by the standby. Is the sport 100 percent clean? No way. Just this week an Iranian player was banned for Clenbuterol.

But neither do I think "tennis has a steroid problem" as one seditious site suggests. Again, it's tough: we've burned my Marion Jones and McGwire and a seemingly unending list of cyclists and track stars. We're well within our right to be suspicious and skeptical. We know the warning signs, such as the mediocre journeyman who makes a sudden mid-career surge. You don't want to be gullible. But you sure don't want to be wrong, either. These are career-wrecking, legacy-staining allegations. You damn well better be right.

With the recent debates around whether Wozniacki, Safina and Jankovic should have reached No. 1 without a major I'll ask about the other side of the game. Have any men ever reached No. 1 without winning a major? --Ravi D, Briarwood, N.Y.

• I'm giving Sharko his Columbus Day off and stating my belief that only Marcelo Rios gets the honor, such as it is. This is neither to condone nor condemn but it seems to me that the, um, singular playing schedule of Serena Williams is really at the root of the issue. If she played a halfway conventional schedule -- backing up her Slam success with a modicum of smaller titles -- we wouldn't be having this discussion. (Of course, the flip side: How can the rest of the field allow someone who only plays six events all year to reside in the rankings penthouse!)

What do you think of Nadal's chances of winning the "Serena Slam"? And if he wins the Australian Open, how about his chances at the "Navratilova Slam"? I know, I know, I'm getting a little ahead of myself and, of course, Nadal needs to remain healthy in order to accomplish any of the above, but could this be more than wishful thinking? I don't see Delpo pulling a Clijsters and winning the first Grand Slam he enters after his layoff, and I think when it comes to the Slams, Nadal edges Djoko and Fed. (Murray who?) --Travis, Washington, D.C.

• Given Nadal's play at the previous hardcourt event -- the 2010 U.S. Open -- it's hard, if not insane, to pick against him in Australia. The guy lost one set in seven matches! He's won in Melbourne before. He's among the players least likely to be bothered by extreme heat, a factor that makes it hard to back Djokovic. Anything obviously can happen -- one of the core reasons we love sports -- but Nadal's looking like a heavy favorite to win, and thus pull off the "Serena Slam." Who, this side of Jonas Bjorkman (see below), wouldn't make Rafa the favorite?