TENNIS.com Saturday picks:

Roger Federer (SUI)[1] v. John Isner (USA)Arthur Ashe Stadium – 3rd match

Andy Roddick said it all: “Isner’s going to be very tall and Roger’s going to be very good.”

Take away the 6’9” Isner’s serve, and this would be a contest between a lion and a baby rabbit. By lofty pro standards, Isner has only semi-decent movement, decent touch and barely-decent groundstrokes, so once a point begins, it’s all over. Federer’s service games should also be easy for the Swiss world No. 1. The only question that remains is how Federer will do with Isner’s serve.

The obvious places to look for indications are Federer’s previous encounters with 6’10” Ivo Karolovic. Goodness knows how Andy Murray came up with this stat off the top of his head (Brad Gilbert?), but according to him, “Federer's played Karlovic three times and only broken him once.”

Even then, it's not an exact comparison – Karlovic’s first serve is a bigger ace machine so far, but Isner’s second serve is also super tough. Still, it’s all we’ve got to go by.

Remember too that Federer’s not particularly fond of high-bouncing balls to his backhand, and Isner’s deliveries leap like kangaroos. If the rookie American has any sense, he’ll begin by targeting that wing. And if he can keep holding his serve and take a few big swings on his returns during the tiebreak, anything can happen.

Or at least, anything can happen in one tiebreak/ But two? Three? The chances get much smaller, and Federer will probably begin to pick up on the serve as the match goes on. As a result, the feeling here is that the contest won’t be that tight. The score may not be one-sided because Isner will be able to hold repeatedly, but it's hard to think of him actually getting close to pulling off a win.

For his part, Federer’s not even thinking about tiebreaks. His ominous-sounding plan is to “...break him early, yeah, break him apart and beat him.”

One thing’s for sure. All eyes – including those in the locker room – are going to be on this match when it begins.

Prediction: Federer

Feliciano Lopez (ESP) v. Donald Young (USA)Louis Armstrong Stadium – 2nd match

Two talented lefties who weren't really expected to be around this far into the tournament. Lopez upset former finalist Juan Carlos Ferrero and then survived a fifth-set tiebreak against Igor Andreev to get to this point, while Young defeated Chris Guccione and then got a walkover from Richard Gasquet.

Young’s star has risen quickly over the summer – he won the Wimbledon boy’s title in July, won his first challenger in August, won his first tour match last week, and won this first Grand Slam match this week. Gasquet’s withdrawal deprived him of the chance to win consecutive ATP matches for the first time, but he’ll have another shot here. This is a winnable match, chiefly because Lopez is mentally suspect and can produce strings of errors when things start to get away from him.

But if the Spaniard remains in the solid frame of mind he’s shown so far this week, Young will have to fashion the win himself. That means dealing effectively with Lopez’s big serve and pushing him well behind the baseline so he’s forced to slice defensively on the backhand. Not that easy for the still-undersized Young, though he may benefit from the fact that he didn’t have to play a second-round match while Lopez had to come through a marathon two days ago.

If Lopez plays up to his abilities – always an if – he should prevent Young from moving on to a dream match-up with Federer in the fourth round. But coming in fresh and with some confidence under his belt, Young’s not likely to just give this one away either.

Prediction: Lopez

Anna Chakvetadze (RUS)[6] v. Sania Mirza (IND)[26]Court 11 – 2nd match

This matchup has been a familiar sight on weekends this summer – the two met in the semifinal of Cincinnati and the finals of Stanford, and also faced off on the doubles court. The Russian likes to mix up her shots while India’s best-ever female player likes to blast away with her big forehand, so we should be in for an entertaining contrast if both are playing well.

Mirza wasn’t the last time they met, going down in two easy sets. Chakvetadze, meanwhile, was in the midst of playing herself to a standstill and eventually came down with a virus, but at least it got her some rest coming into the US Open. Both have been fairly solid during their two matches so far. Chakvetadze's variety is usually effective at getting Mirza on the move, so give her the edge. But if Mirza goes for the early strike and is firing accurately, she could reverse the result this time around.

To add some intrigue to the mix, both Chakvetadze and Mirza have worked with Patty Schnyder’s husband and coach Rainer Hoffman for short periods during this year. And the winner could face Schnyder next.

Prediction: Mirza