LONDON,  (Reuters) – Defending champion Roger Federer  joined the party yesterday but American warrior John Isner’s  Herculean efforts finally caught up with him as his surreal  Wimbledon adventure came to an abrupt and weary end.

Isner’s freakish 11-hour first-round victory against gallant  Nicolas Mahut re-wrote the tennis record books and overshadowed  pretty much everything else on offer over the first four days,  including a first visit by Queen Elizabeth since 1977.

As the eye-popping statistics churned out of the gargantuan  contest on Court 18 during Wednesday and Thursday, six-times  champion Federer’s obvious unease in two scratchy victories  against lowly-ranked players was largely overlooked.    The 28-year-old Swiss dined with the Queen on Thursday and  he returned to the All England Club looking like the player who  has reigned at Wimbledon for most of the last decade.

Against Colombia’s Alejandro Falla, who was three points shy  of a senstaional first-round knockout on Monday, Federer looked  awkward and error-prone and he was only slightly better against  Serbia’s Ilija Bozoljac in round two.

Against experienced Frenchman Arnaud Clement on Centre Court  Federer’s game clicked back into gear as he moved into the last  16 with a classy 6-2 6-4 6-2 victory.

“This felt much better,” the top seed, who faces Jurgen  Melzer on Monday, told reporters. “Right off the bat I got the  early break. Same thing in the second set. From then on, it was  a race to the finish line.”

The top half of the draw is now taking shape nicely with  third seed Novak Djokovic, fifth seed Andy Roddick and French  Open semi-finalist Tomas Berdych all into the fourth round.

Lleyton Hewitt, who beat Federer in the Halle final, is also  in the mix after grinding down Frenchman Gael Monfils to set up  an enticing clash with Djokovic, who thrashed Spanish  claycourter Albert Montanes.

Isner’s astonishing 70-68 victory over Mahut was the longest  tennis match that is ever likely to be played and asking him to  return to court 19 hours later looked a little cruel.

From the moment he walked gingerly out on Court Five to face  Dutchman Thiemo de Bakker, whose own 16-14 deciding set win in  the first round looked like a piffling inconvenience, Isner  looked spent and he lasted just 74 minutes.

His 6-0 6-3 6-2 was the shortest men’s singles of the  tournament so far and the most telling statistic was the  complete lack of aces against his name compared to the 112 that  whistled past Mahut’s racket. Talk about extremes.