American Mardy Fish continued his rejuvenated run on the ATP World Tour, showing off his career-best form in a hard-fought 4-6, 6-4, 7-6(4) win over countryman John Isner on Sunday at the Atlanta Tennis Championships.

Coupled with his triumph two weeks ago in Newport (d. O. Rochus), the 28-year-old Fish extended his winning streak to 10 straight matches. He was contesting his third final from his past four tournaments, beginning with a runner-up finish to Sam Querrey last month at The Queen’s Club.

"This is as top as I’ve ever been," said Fish. "I’ve never won two tournaments in one year, I’ve never won two tournaments in a row, and on the ATP [World] Tour, I’ve never won 10 matches in a row. It’s probably as good as it’s been. "

He collected $95,845 and 250 South African Airways 2010 ATP Ranking points as the winner of the ATP World Tour 250 hard-court tournament, while Isner earned $50,500 and 150 South African Airways 2010 ATP Ranking points.

The Atlanta champion also assumed the lead in the Olympus US Open Series standings following the first tournament of the North American hard-court swing.

Fish had made his way into final without dropping a set in four matches, including an upset over top seed Andy Roddick in the semi-finals, but was made to work hard for the victory in sweltering conditions Sunday after his opponent claimed the only service break of the opening set.

With Isner poised to close out a straight-sets win, Fish stepped up to break his opponent twice in the span of three games – allowing him to level the match at a set apiece and go up 3-1 in the decisive set. The lead proved short-lived, however, as Isner immediately broke back and forced Fish to fight off another break point chance in the ninth game.

Fish took control in the tie-break as he won the first four points, and though Isner countered by winning the next three, the No. 6 seed held on to clinch the two-hour, 45-minute win on his second match point.

"It was a little lucky to pull through," said Fish. "Today was an extremely physical match just with the heat. He’s no fun to play, that’s for sure. He gives a lot of people a lot of trouble."

The former World No. 17, who has shed 30 pounds over the past year, improved to a 5-11 mark in ATP World Tour finals. Since falling outside the Top 100 this past March, he has been climbing back up the South African Airways 2010 ATP Rankings and entered Atlanta at No. 49.

He said: "It feels great, obviously putting in the work. This is what we wanted to do. This is where we wanted to be. These are the types of matches we targeting in October when we were rehabbing the knee. It feels like a long time ago. It feels great."

World No. 19 Isner fell to a 16-6 mark in matches decided in a final set tie-break. In his second-round opener – his first singles match since Wimbledon – he had saved two match points before edging Gilles Muller in a tie-break.

The 25 year old, a four-time All-American at the University of Georgia, was looking to win his second ATP World Tour title after opening 2010 with victory in Auckland. He also reached the finals this season at Memphis and Belgrade, both times falling to Querrey.

"This is the third final this year that arguably I could have won," said Isner. "I lost two finals earlier this year when I was up in both of them, one of them I was serving on match point. This one could’ve gone either way. It’s disappointing.

"I’ve made four finals this past year and I’ve lost my last three all in three sets. That’s hard to swallow, but it hasn’t stopped me from progressing. I know if I keep putting myself in this position it’s going to happen, and I know I will keep putting myself in this position."