By John Stonestreet

LONDON (Reuters) - American 18th seed John Isner ended the Wimbledon odyssey of Australian qualifier Matthew Barton on Friday, serving his way to victory 7-6(8) 7-6(3) 7-6(8) in a high-octane second-round clash.

The 6-foot-10 (2.08 meter) American fired down 43 aces, including a 142 mph bullet that was the joint fastest of the tournament.

He was forced to knuckle down by the gritty Australian, at 248th the lowest-ranked competitor left in the men's singles draw.

Barton, whose rasping forehand drives often had Isner scampering and who struck 16 aces of his own, saved five set points in the first set and drew a howl of triumph from the American after he converted the sixth with another howitzer serve.

Isner now boasts a trio of third-round appearances at the All England Club and has reached the last 16 or better at the other three grand slam events.

In contrast Barton was playing his first grand slam event, and the 47,000 pounds ($62,000) he received for losing Friday's match was close to half as much again as he had earned throughout a professional career that began in 2009.

He would have been a spectator this time around too, but for a last-minute withdrawal from the Wimbledon qualifying competition at Roehampton.

The final man accepted into that event, Barton came through three rounds to face another qualifier, Frenchman Albano Olivetti, in his All England Club debut.

That match, interrupted by rain on Tuesday and again on Wednesday, turned into the second longest of the tournament so far, Barton coming through 14-12 in the fifth set on Thursday after a shade over four hours' play.

Isner is familiar with marathons over three days, having won the longest match in Wimbledon history in 2010 when he beat another Frenchman, Nicolas Mahut, in just over 11 hours after a 138-game final set.

Compared with that, Friday's win was little more than a stroll, the American taking the second set with a clean volley winner and fighting back from a break down in the third to close things out in a third tiebreak in two hours 17 minutes.

Isner plays French 12th seed Jo-Wilfried Tsonga in the third round.

(Editing by Ed Osmond)