John Isner.  Gael Monfils.  The average tennis fan has probably heard of one, but not the other, and possibly neither.  Monfils, the talented and athletic Frenchman, would seem like the shoo-in favorite to beat John Isner.

Yet, if you looked at their head-to-head, it’s Isner who leads 2-1, and all 3 meetings have been closer.  Isner, like Karlovic, has one weapon that works really well, and that’s his serve.  This means, more likely than not, he’ll hold serve, and then take his chances in the tiebreak.

It was a surprising opening to the match when Isner took a quick 6-1 first set.  However, Monfils came back to take the second set 6-4.  The last two sets only saw each player break the other once.  Both sets went to tiebreaks, and both went to John Isner.

Isner wins: 6-1, 4-6, 7-6(4), 7-6(5).  A bit of an upset, but still leaves 2 American men in the Aussie Open.

Speaking of big servers, Ivo Karlovic has taken his upset of Radek Stepanek and played his way into the fourth round.  He faced his bald compatriot, Ivan Ljubicic, in four sets, 6-3, 3-6, 6-3, 7-6(7).  Everyone says Karlovic is all serve, but there was only one tiebreak in the four sets, showing his return game must be decently solid too.

Up until Chennai, Marin Cilic had never beaten Stanislas Wawrinka in 4 attempts.  Cilic, touted as one to watch for, defended the title in Chennai and had his first win.  Could he do it again?  Turns out yes, he could.  Four set win over Wawrinka: 4-6, 6-4, 6-3, 6-3.

Fernando Gonzalez, whose best results in a Slam have been at the Australian Open, had his hands full with Marat Safin Lite, er, Evgeny Korolev, who looks a lot like young Safin.  Gonzalez needed five sets to win this: 6-7(5), 6-3, 1-6, 6-3, 6-4.

Finally, the big gun.  Of the top group of players playing today, Andy Murray had the easiest win, over Florent Serra of France.  The first set was a bit iffy.  Murray had a 3-0 lead, then let Serra break back to 3-all, then got another break, then got broken back again, before finally breaking to win the first set.  At the end of the first set, while doing pirouettes to chase down overheads, Murray appeared to twinge his back.  This seemed potentially game changing, and there was a brief scare whether Murray would even finish the match, but the pain seemed to go away.   Serra did what most players try to do against Murray which is to take the game to him and make him run.  Murray always looks a bit challenged, and one wonders if he’s doing the right thing by playing so passively.  But, of the top guys, he was the only one to win in straights.

Nadal looked like he’d win his in straights.  Kohlschreiber hits the ball decently hard off both sides and tried to take the game to Nadal and for a while Nadal was struggling with Kohlschreiber’s game, but just when Kohlschreiber looked like he would break through, he’d make an error or Nadal would play just good enough of a point.  It looked like Nadal was headed to a straight set win, but it took four sets, with Kohlschreiber grabbing the third set, 6-2, and Nadal needing to go 7-5 in the fourth set (2 breaks of serve to Kohlschreiber’s one break) to win.

If Juan Martin del Potro is really hurting, it’s hard to tell, because while he hasn’t been dominant winning his matches, he still wins them.  del Potro dropped a set, 6-0, to German Florian Mayer after winning the first set, 6-3.  He took the next two sets 6-4, 7-5.  It seems del Potro is somewhat vulnerable, but he also plays tough when he has to.  In any case, he’s headed to the fourth round.

Andy Roddick faced his toughest challenge so far.  Although Roddick has never lost to Feliciano Lopez in 5 attempts dating back to 2003, Lopez is a bit like Verdasco lite.  Big serve, big enough lefty forehand.  Except for possibly the serve, Verdasco does everything better than Lopez.  Roddick tried to softball Lopez some, and found himself down a set after one set.  However, he fought through three tough sets to win in 4, and maintain his perfect record against Lopez.

The bottom half of the draw leads to some intriguing matchups: Roddick plays Gonzalez, Cilic plays del Potro in a rematch of their US Open encounter, Murray plays Isner, and Nadal plays big-serving Ivo Karlovic.

In the top half, perhaps Hewitt-Baghdatis provides the most intrigue.  These two played a marathon match at the Australian Open a while back that went to four in the morning (Hewitt won).  The other interesting match is Jo-Wilfried Tsonga against veteran, Tommy Haas.

As Martina Navratilova says, the tournament doesn’t really start to get serious until the second week, and with one more round, we’re almost there.