They are the faces of U.S. tennis, but not household names. They have had breakout moments, but not the big-stage triumphs that create superstars.
For world No. 20 Sam Querrey and No. 23 John Isner, the Davis Cup could be their chance to shine. They are the foundation of the American team that will take on Serbia and No. 1 Novak Djokovic starting Friday at Taco Bell Arena.
Isner, who will face Djokovic on Friday, has won five of his past eight Davis Cup matches - including road upsets of current top 10 players Roger Federer (Switzerland) and Jo Wilfried-Tsonga (France) last year. He's 6-6 overall.
Isner figures three of his five best matches last season were in Davis Cup ties.
"It brings out the best in me," he said Monday morning after practice at Taco Bell Arena. "You're not just playing for yourself - you're playing for something a lot bigger than yourself and most importantly you're playing for your country."
Isner, who is best known for his 140 mph serves and record 11-hour, 5-minute Wimbledon match in 2010, could use a spark. A knee injury forced him to skip the Australian Open and limited him as he split two matches in the Davis Cup first-round win against Brazil. And in the last two tour stops - both marquee events - he went 1-2.
"I'm healthy - it's not a matter of that," the 27-year-old said. "I just haven't been playing my best this year. That's just how it goes sometimes. I'm not fretting about it. I'm just trying to stay positive. I know that when my game comes around, and I believe that it will, I'll be a very tough person to beat."
That, U.S. captain Jim Courier said, is Isner's trend.
"He's a momentum player," Courier said. "It seems like when he gets one good week under his belt, he just runs for four or five months. Hopefully it will be Boise that gets him started."
Isner is a unique talent on the ATP World Tour.
He's 6-foot-10 - an inch taller than his tour bio reports and 7 inches taller than he was at 17 - and the king of aces. He also is a self-described "late bloomer," who went to Georgia with no pro aspirations, became the NCAA's top-ranked player and won team and doubles national titles.
His matches often are endurance tests. He has played in three of the 10 longest U.S. Davis Cup matches since the introduction of the tiebreaker in 1989 and his past four Grand Slam appearances ended with five-set losses.
Isner's game is built around one shot - his homemade serve. He led the tour in aces with 16.8 per match last season.
"It's sort of always been a natural motion for me," he said. "No one really ever taught me how to serve. It's something I just picked up. And no one messes with it either. It is my best shot. It's the shot I rely on most and I'm going to continue to rely on the most. In order for me to do well, I have to have my serve going well."
When it is, that serve is a disruptive force.
"I don't want to give my opponent too much rhythm," Isner said. "I'd rather me not have rhythm as well as my opponent not have rhythm because most guys I play against want to find that groove in the match and once they do, they're very, very tough to beat. For me, I try to take that away. It's something I know I have to do against Djokovic."
Isner beat Djokovic for the first time last season and spent 18 weeks in the top 10 while earning $1 million-plus for the third straight year. He dropped to No. 14 by the end of the year and has slipped another nine spots through his struggles this year.
"One of my goals, when I realized I was a pretty good player, was I wanted to get inside the top 10," he said. "I also knew that once you get there, the hard part is staying there - and that's where I'm not right now. I know I'd like to get back. I'd like to stay there longer."
Querrey jumped Isner in the rankings last month - becoming just the 13th man to hold the title of No. 1 American since the computer rankings began in 1973.
He's in the same mold as Isner - a 6-6 power player who has played the second-longest match in Wimbledon history (a mere 5:31).
"Serve and forehand, those are my bread-and-butter shots," said Querrey, who hangs out with Isner on the road and plays doubles with him. "He might come to the net a little more than me, but we pretty much have the same style of game."
Like Isner, an injury derailed Querrey when he was at his peak. He won a career-high four tour events in 2010 but underwent elbow surgery in June 2011. It took about a year for him to return to form - posting a 24-11 record in the second half of last season and a 13-7 mark so far this season.
He also beat Djokovic for the first time last year and survived the pressure-cooker of a decisive fifth match to clinch the U.S. win over Brazil in February.
"It was fun," Querrey said of the victory in Jacksonville, Fla. "I was glad to just get through it and help us get to this next one here. It was a great stepping stone for me and a great team win."
Querrey is 3-5 in five career Davis Cup ties. He enters this one, for the first time, as his nation's top player.
"It's exciting," the 25-year-old said. "All the guys have had their chance, so it's fun to finally get mine. But I've got all the other guys nipping at my heels. They're working hard to take it back. And I'm working hard to keep it."
Chadd Cripe: 377-6398, Twitter: @IDS_BroncoBeat