In tennis, like all sports, you can be in top shape physically, but what a difference a year can make. Especially when you're up against the best week in, week out.

Defending champion Andy Murray's surprise loss to Mardy Fish in the Sony Ericsson Open in Miami on the weekend, proves just that.

Murray is in good company, as world no.2 and runner up to Andy in Miami last year, Novak Djokovic, suffered the same fate, losing his opening match to the diminutive Olivier Rochus. So two of the big four were gone.

Miami also played havoc for women's No.1 seed Svetlana Kuznetsova, the Russian suffering a straight-sets loss to France's Marian Bartoli. Kuznetsova was clearly troubled by a nagging shoulder and had three on-court treatments. But that's not to take anything away from Bartoli who has now won seven of her past 11 matches against top five players, and let's not forget she has a Wimbledon singles final on her CV.

No such travails for Roger Federer, No.1 seed in the men's draw, who had to work to get to the fourth round over Frenchman Florent Serra. With his usual clinical disposal shelved for this match, Federer went into ‘work horse mode', and squandered handy leads in both sets and instead needed two tie-breaks to advance.

True to form, Federer remained in a positive frame of mind, post-match, grateful for the tie-break play, which, by his own admission, doesn't often happen. Meanwhile, Rafa Nadal is winding up for a possible showdown with Roger in the final, something that hasn't happened since last May. Who would have thought that a year ago?

Two shining examples of comeback momentum in the past year are Belgian duo Justine Henin and Kim Clijsters, who remain in contention in the quarter finals. The unseeded Henin, as foreshadowed in this column three weeks ago, again knocked out the hapless Elena Dementieva. Surely the Henin carnage of seeded players by virtue of her non-protected ranking, which commenced in Australia, will not be repeated in the future? At least Henin will now be officially in the top 30 in the rankings post-Miami, enough to get her seeded at the French Open.

Aussie Sam Stosur, in her first tournament as a top-10 singles player, outpointed Jelena Jankovic in their fourth-round bout, thereby defending ranking points claimed in Miami last year where she made the quarters. Jankovic's eight-match winning streak was broken by Stosur who previously hadn't managed to claim a set against her higher ranked opponent in their three encounters.

In the locker room, three consecutive losses entitles your opponent to refer to you as a "pigeon", quite an unflattering description in tennis parlance, and also a little harsh when you consider Jankovic finished 2008 ranked as world no.1. This time around, with an 11-9 win in the second set tie-break, Sam clearly played her ‘A' game and the past is the past. The Queenslander is performing admirably, locking down her top-10 status, and another tournament victory may not be too far away. But first things first, a quarter-final match up with Kim Clijsters, with the winner to play the "floater" Henin or US Open runner up, Caroline Wozniacki. Watch this space.

Miami was less generous to the Aussie men, with no Aussies in qualifying and only Pete Luczak in the main draw, who went out in the second round. We look forward to Lleyton Hewitt's return to the scene in hopefully a few weeks, as there's no one better to fly the flag for the Aussie men than Lleyton. In fact, that's been a constant, year in, year out.