Brazilian Thomaz Bellucci, the world No. 35, is not a pushover. He demolished the relentless David Ferrer in Monte Carlo on clay last year and Janko Tipsarevic in the final at Gstaad. He's taken a set off Roger Federer twice and one off Novak Djokovic.
A left-hander with a big serve, Bellucci is like most players ranked in that 30-50 range: hampered not by insufficient weapons but by consistency. He's what opposing coaches and commentators would call a "tricky matchup," where he is hardly ever the favorite but isn't a guy anyone should take lightly either.
So his victory over John Isner last week in the fourth rubber of the U.S. versus Brazil Davis Cup tie in Jacksonville, Fla., wasn't as surprising as, say, Sam Querrey's victorious but serious struggle against noisy, unheralded 135th-ranked Thiago Alves in the clincher.
The importance of Isner losing is not reflected by his one-on-one matchup with Bellucci but by where he was at this time a year ago, where over a two-month period he had beaten Federer and Jo-Wilfried Tsonga in Davis Cup and Djokovic at Indian Wells, losing to Federer in the final. From that streak, Isner knew he belonged and said as much.
"When I step on the court, with my serve, I believe I can beat anyone," he said at Indian Wells. His opponents were on notice.
Isner had become "The Guy You Don't Want to Play." He pushed into the top 10. The bigness of his game transformed his weaknesses from chronic to correctable. Once he smoothed out his wrinkles, he had the firepower to be major contender material.
The problem is that Isner's game hasn't matched the expectations created by that run last year, which, incidentally, placed him at a career-high No. 9 in the world. In all four majors last year, Isner lost in five sets, failing to reach the quarters in any of them.
While the supersized portions of Isner's game -- the big serve and forehand combination -- allow him to be scary, his fatal imprecision, inability to break serve, lack of balanced footwork that creates massive unforced error counts on both wings and the questionable stamina is what makes him ripe for upset against the Belluccis and Paul-Henri Mathieus of the world.
The Isner conundrum matters because a lingering heart ailment has made Mardy Fish's status a mystery. Andy Roddick is gone. Isner (now No. 16) and Querrey (No. 20) are the American standard-bearers. The first and fourth rubbers of a Davis Cup match now belong to Isner. The draw of a major will -- at least along these shores -- focus on Isner and his chances to get deep in to the second week.
Isner missed last month's Australian Open with a knee injury and flailed badly to end the 2012 season. He is one of the most candid players on tour and has admitted that, in addition to the inconsistencies of his game, he is not playing with a high level of confidence.
Since beating Jarkko Nieminen in the second round of the U.S. Open, Isner has lost three of his last four Davis Cup matches and eight of his last 11 matches overall, which doesn't include two exhibition losses to Kevin Anderson and Tsonga at Hopman Cup.
As the American No. 1, Isner is charged with projecting confidence not just for himself but as the player toward other American players will look, just as he and younger Americans did with Roddick. Whether he is ready or not, Isner has entered a new stage in his career. He is the leader.