WIMBLEDON, England -- Marathon man Isner looked weary from the outset Friday, required treatment for a neck injury and was beaten by unseeded Thiemo de Bakker of the Netherlands 6-0, 6-3, 6-2.
The second-round match was over in just 1 hour, 14 minutes, and the five games won by Isner is the fewest by a male player this week.
It was a complete turnaround from Isner's epic three-day victory over Nicolas Mahut, which lasted 11 hours, 5 minutes and went to 70-68 in the fifth set.
What's more, Isner served no aces Friday after hitting a record 112 against Mahut.
"I've never been this exhausted before," Isner said. "Mentally and physically, I was obviously a bit drained. I just didn't have much in the way of my legs. I was just low on fuel out there. Didn't really have a chance."
Starting shortly after noon in warm sunshine, Isner received a standing ovation when he walked onto court. He immediately lost his serve -- something that didn't happen once in his never-ending fifth set against Mahut.
"The turnaround time -- he just didn't have enough time to get his body right," said Isner's coach, Craig Boynton. "He's one tired boy."
Federer looked perfectly fresh as he demolished Clement 6-2, 6-4, 6-2, playing like the old grass-court master himself after being stretched to five sets in his first-round match and four in the second.
In women's play, five-time champion Venus Williams moved into the fourth round by beating Russia's Alisa Kleybanova 6-4, 6-2. Williams was down 3-1 in the first set before taking control with her power game as both players went for big shots from the baseline.
Williams took a tumble in the last game as she slipped on the grass, but appeared unscathed. The No. 2-seeded Williams next faces Australian Jarmila Groth, and could eventually meet top-ranked sister Serena in the final.
Justine Henin and Kim Clijsters -- two Belgians making Wimbledon comebacks -- won in straight sets to set up a fourth-round showdown Monday.
Clijsters, seeded eighth, beat No. 27 Maria Kirilenko 6-3, 6-3. Henin, seeded 17th, defeated No. 12 Nadia Petrova 6-1, 6-4.