Roddick, Federer should advance

England breathes a sigh of relief that Tim Henman is in the second week again. Roger Federer is playing like he's totally comfortable being the favorite. Past champion Lleyton Hewitt is playing his best tennis since he won the title. Andy Roddick looks more and more comfortable on grass with each passing round.

Here's a look at the fourth-round matchups:

Roger Federer (1), Switzerland, vs. Ivo Karlovic, Croatia

Based on how Federer's been playing, this might appear to be a routine match, but Karlovic's height (6-foot-10) makes him an awkward opponent. It's hard to get a rhythm against him.

It's easy to look past Karlovic and put Federer in the next round. It's conceivable that Federer might lose a set here, but still you'd have to be crazy not to pick him to win.
Pick: Federer

Carlos Moya (9), Spain, vs. Lleyton Hewitt (7), Australia

This is one of the two fourth-round matches where the seeds who were supposed to be here got here; the other match is between Tim Henman and Mark Philippoussis. These two seeds are closest in placements, and their head-to-heads are close, too.

The edge goes to Hewittt, though, as a past champion. Hewitt seems to be more mentally focused than in the past 12 months. He's playing aggressively enough, yet not committing too many unforced errors. He's playing almost as well as he did two years ago. Even though Moya is one of the Spaniards who can play well on grass, there's a level of insecurity on the surface.

Pick: Hewitt

Florian Mayer, Germany, vs. Joachim Johansson, Sweden

Both are doing a lot of things for the first time: They're in the round of 16, this is the farthest they've gone in any major, and it's the first time they've met. They're close in age, Mayer is 20 and Johansson turns 22 this week; it comes down to who feels most comfortable in the biggest match of their career.

Johansson has played some Davis Cup matches under heavy pressure. He's ranked higher by 23 points and has one of the biggest serves in tennis.

But who knows what will happen because neither one has anything to lose and neither has been in this situation before.
Pick: Johansson

Sebastien Grosjean (10), France, vs. Robby Ginepri (27), United States

Ginepri is getting better with each match at the All England Club. He started off the first set of the tournament looking really sluggish. Although you wouldn't think of Ginepri as a grass-court player, he did win Newport last year. He has great returns and stays calm, cool and collected.

He's going to need to do all that and then some against Grosjean, whom he has never beaten and lost to at the Australian Open in four sets. Grosjean is a returning semifinalist at Wimbledon and is really one of the more entertaining all-court players in tennis.

You have to give the edge to Grosjean for his experience and recent grass-court record. He reached the final of Queens' for a second consecutive year. So in the past two years, Grosjean is probably right behind Federer and Roddick in grass-court matches won.
Pick: Grosjean

Tim Henman (5), Britain, vs. Mark Philippoussis (11), Australia

Philippoussis has beaten Henman before at Wimbledon and holds a 4-2 edge over Henman. They haven't played in 2½ years. Their head-to-heads don't mean that much except their games haven't changed that much. They both play serve-volley, but Henman plays with less power and more to the percentages whereas Philippoussis is more about raw power and risk taking. Just gigantic tennis.

The match is more in Philippoussis' hands. If he is playing well, no one can beat him. He's that good. This is the first glimpse we've had of him in-form all year. So, this match against Henman will show whether he's back at the level he was last year as a finalist at Wimbledon.

Perhaps he's gotten through to this round so far with a bit of bluff, so you have to go with the tactical shot-making of Henman over the blast-away high-risk tennis that Philippoussis plays.
Pick: Henman

Xavier Malisse, Belgium, vs. Mario Ancic, Croatia

Three years ago, Malisse could have gotten to the final but lost to David Nalbandian in the semis. He's on another run on the grass courts, giving the country of Belgium something to cheer for with Kim Clijsters and Justine Henin-Hardenne out of the tournament.

As this is their first meeting, there's no way to know how they match up against each other, but Ancic has a great grass-court game. If you were handicapping this, it would be very close. With Malisse's grass-court record and experience, this could go to a fifth set.
Pick: Malisse

Vince Spadea (30), United States, vs. Sjeng Schalken (12), Netherlands

Vince Spadea deserves to be applauded for his continued resurgence. He ended his record losing streak two years ago against Greg Rusedski at Wimbledon. You wouldn't expect him to feel good on grass, but he does.

They're tied head-to-head and have never played on grass before. But Spadea, with the shine of being selected for the Olympic team and his best run at Wimbledon ever, will chew up some of Schalken's weak serves and find a way to win the match.
Pick: Spadea

Alexander Popp, Germany, vs. Andy Roddick (2), United States

This is a little bit like the Federer-Karlovic match. Roddick, like Federer, starts the heavy favorite -- only instead of a 6-10 opponent, he faces Popp, who is listed as 6-7.

Popp has an unusual record at Wimbledon, having only played it twice before and gotten through to the quarterfinals each time as a total outsider. As with Karlovic, it's not easy to get a rhythm against Popp. But Roddick played his best match of the tournament against Taylor Dent in the last round. Roddick held on in the tiebreaks to win it in three sets. He should be too good for Popp, but he might have to play a couple more tiebreaks.
Pick: Roddick

ESPN tennis analyst Pam Shriver won 21 singles and 112 doubles crowns, including 22 Grand Slam titles.