!Delpo 
By TennisWorld Contributing Editor Andrew Burton

For a while, like many people living in the US during the last decade, I became actively interested in poker.  Much of ESPN's daytime programming was taken up with the game (I don't think it can be called a sport).  You'd watch as 22 year olds in hoodies and sunglasses shovelled all their chips into the center of the table and grizzled 70 year old Texans impeturbably muttered "call."  Then the dealer would discard a card, turn the next face up, and either the Texan or the lad in the hoodie would be a few million dollars richer.  Easy money, no?

Sadly, it turns out that these dramatic head to head face-offs, almost literally made for television (poker on TV only took off with the invention of hole card cameras and the use of computers to display the odds for each player) were the exception, not the rule.  In tournaments, very few hands end with any kind of showdown between two players.  Players know the percentages inside-out, and know that going for too much, too soon, is the quickest route out of a tournament.   The majority of hands are played cagily, with the big pushes often being reserved for desperation plays as a player's stack dwindles (the best recent book on big time poker is James McManus' "Positively Fifth Street").

Similarly, the moments we remember from classic tennis matches tend to be the great winners: shots like Nadal's fizzing forehand pass at 6-6 in his tiebreak with Ivo Karlovic on Thursday evening.  But in singles matches, winners are comparatively rare when compared with other shots.  I'm not talking about unforced errors, or even forced errors, both of which (like winners) are point ending shots.  In the modern power baseline game, the majority of shots after the serve and return occur in the context of neutral ball rallies, where both players are standing on or near the baseline, and neither player has an advantage due to the other being out of position or having left the ball too short on the last shot.  What players do next tells us a lot about their attitude to the game, and it's one aspect of the professional game a recreational player can genuinely adapt to his or her own way of playing tennis.

I was courtside at Stadium 2 earlier this week for the Cilic-Wawrinka and Del Potro-Kohlschreiber matches.  Both matches had a high percentage of neutral ball rallies.  A neutral ball rally typically begins on the third or fourth shot in a rally: neither the server nor the returner establishes a clear advantage with the first two shots of the point, so both players make sure to play the next ball deep (closer to the baseline than the service line) then to set up across the net from the opponent in optimal position (depending on the angle of the shot, this can be in the center of the court, but it's common to see players offset at a slight diagonal, either both slightly on their own deuce side trading forehands, or on the ad side hitting backhands).

What happens next depends, of course, on the way each ball is struck, but you also get to see the  players' styles and approach to the game of tennis in these rallies.  Broadly speaking, a player can do one of two things, assuming that the ball coming towards him is relatively easy to handle at his or her skill level: attempt to make the opponent's next shot significantly more difficult by playing with increased pace, spin, or hitting the ball closer to the sideline or baseline (ie making an aggressive move); or playing the ball back with lots of margin, perhaps with some minor variation of pace or spin, but staying well away from the net and the sidelines.  Let's describe this as staying neutral.

Of the four players, Marin Cilic was the most likely to play a neutral shot in a neutral ball rally, then Del Potro, then Wawrinka, with Kohlschreiber being the most likely to attempt to up the pressure first in a rally.  Each of the players would readily take control of the point if they got a short ball, but Cilic virtually never attempted to dictate play from the baseline.  Kohlschreiber and Wawrinka both have a potent one handed backhand which they can hit down the line, which is quite unusual in the mens' game; Wawrinka would often engage Cilic in a backhand to backhand rally then catch his opponent by surprise with a flat drive into his deuce corner.

It wasn't obvious to me whether temperament or technique was the more important factor in determining where a player would fall in the aggressive/neutral scale.  Kohlschreiber hit several volleys with impeccable technique, and Wawrinka has been carrying his Swiss colleague with his own net play in the doubles here at Indian Wells.  On the other hand, if you think that you can make your opponent go for too much through impatience, or your passing shots are the best feature of your game, then obeying the old medical injunction - "First, do no harm" - is your prime directive.

If I had to make the choice, though, I'd put it down to personality: some players are wired to attack, and some aren't.  This is playing out on the Stadium Court even as I write this post: Maria Sharapova is the aggressor on at least 75% of the baseline rallies, but Caroline Wozniacki is soaking up the pressure.  It's one of the classic WTA contests, with some high quality rallies, but so far the advantage is with the defense. [Update: yup, that continued through the second set]

A few words about Saturday's ATP semi finals before I sign off.  When the draw came out, I thought the Soderling/Murray quarter would be the toughest, but neither the no 4 nor the no 5 seed made it past the round of 32.  Federer had tough potential matches with Milos Raonic and Tomas Berdych, neither of which transpired.  A Djokovic-Roddick QF, repeating their match here in 2009 was an appealing prospect - Richard Gasquet had other ideas.

Even if the draw bounced around a bit, we've got four semi-finalists who between them have won all of the last 24 ATP Grand Slam tournaments (Federer 12, Nadal 9, Djokovic 2 and Del Potro 1), plus a re-run of the 2009 US Open semi finals.  There's a chance that we could get the first Federer-Nadal final in North America since Miami 2005, but (to my chagrin) I don't think that's going to happen.  My head tells me that Djokovic's run is going to continue, and my gut tells me that Del Potro will walk out with him on Sunday afternoon.