When Roger Federer tucks his little ones in tonight, he’ll probably pause to have a few words with the newest edition to the family, little Wilson. He’ll probably say:

“You did very well today, I’m so proud of you! Sure, you didn’t exactly behave your best on some of those forehands I shanked, but the cut backhands—wonderful! The retrieves? Superb! Okay, so at the end of those sets you kind of let me down. I mean, when does it take me five set points to win a set? How often, on my own, do I blow five match points and let a guy escape with the game—and maybe the match?

“Sure, I served it out afterward to win it comfortably, 6-4, 6-3. But there’s a lesson in this for you, and you might as well learn it now. It isn’t always going to be Jan Hajek across the net. It could be Novak, or Rafa, or Andy, and that might be a different story. So we’re going to work on this. . . focus, focus, focus! Night-nite, Wilson.”

That’s pretty much how things went on day two of the new-racquet experiment for Federer, whose new frame features a head that is a full eight square inches larger than the 90 square-inch model with which he did all his damage thus far. But Federer is now down to No. 5 in the rankings, and he knows that the larger head size could really help—if it doesn’t turn out to be too much of a transition and end up creating more problems than it solves.

In Hajek, ranked No. 140, Federer was up against a dangerous journeyman buoyed by his upset of Ernests Gulbis yesterday. At the start, Hajek was striking the ball with confidence and pace. He earned a break point in the first game, but Federer dispatched it with one of the many pistol-shot, down-the-line backhand winners he would hit on this day.

Having missed Federer’s opening match in Hamburg, by the fourth game of this one I found myself asking, “Can this new racquet really be making as much of a difference as it seems?” Perhaps I was fooled, but it appeared that Federer was getting a lot more pop on the ball—even if the periodic shanks and unforced errors that have become a part of his game looked even more monstrous.

Given how often—and how effectively—Federer was slicing the ball, and how far back Hajek was behind the baseline during points, I found myself wondering why Federer wasn’t mixing more drop shots into his rally game.

Bingo.

Next thing I knew, Federer threw in a dropper in that 2-1 game and won the ensuing forecourt exchange to reach break point. A forehand cross-court error by Hajek gave Federer the first break of the match and the lead, 3-1.

But Hajek would break right back, albeit with a little luck. At break point in the next game, Hajek’s backhand service return struck the top of the net and dribbled over so gently that when the ball landed on Federer’s side of the court it didn’t even appear to bounce.

Back on serve, Hajek produced a strong hold for 3-3, and had Federer in trouble in the next game. I don’t know if Federer’s problems were related to the still relatively unfamiliar racquet, or just another of those puzzling lapses that begin to haunt players late in their careers. It’s something Federer has struggled with in the past few months.

In any event, Hajek had two break points in the next game, but failed to convert either. The more interesting one was the second; Federer staved it off with a powerful down-the-line backhand winner that seemed to have a little more authority than comparable shots in the past. He went on to hold for 4-3.

After another exchange of holds, Federer began to find his A-game again. A heavily sliced backhand winner brought him two break (and set) points with Hajek serving at 15-40. But Federer was unable to convert—nor could he capitalize on two more break opportunities before he finally won the set on his fifth break point, when Hajek drove a forehand into the net.

Federer didn’t experience a comparable letdown in the second set. He broke Hajek for 4-2 with a prodigious forehand approach winner, and consolidated the break with a very strong game punctuated with an ace. With Hajek serving at 2-5, Federer was unable to convert five match points—all because of his own errors. Granted, he had a big lead by then, but such lapses are worrying for anyone.

Federer probably took some consolation out of the way he closed Hajek out in the next game, which began and ended with an ace, ending the match in one hour and 11 minutes.

The new racquet appears to be explosive, but where it seems most helpful is in creating heavy slice and the extra bit of power it offers when, for instance, Federer needs to make a desperate retrieve to stay in a point, or when he can use a little extra pop in a wrist flick. Federer's flat backhand is lethal, but the distinguishing features of his forehand (including the shanks) are likely remain the same, albeit exaggerated.

Judging by this match, Federer has less to worry about with his equipment than those lapses that I’ve always described as signs of “champion’s fatigue.” He experienced a few those letdowns today, but can ill afford them in the future.