"Tennis today lacks characters," Ernests Gulbis told L'Equipe one year ago after crashing out of the French Open in the second round to Gael Monfils. "I respect Roger [Federer], Rafa [Nadal], Novak [Djokovic] and [Andy] Murray but all four are boring players. Their interviews are boring, they are crap. It's a joke."

Ladies and gentlemen meet Gulbis, the 25-year-old currently ranked No. 17 in the world who has upset Federer and Tomas Berdych on his way to making the French Open semifinals this year. "Boring" is one word that can certainly not be attributed to the Latvian. In fact he has often been called, without a hint of irony, "the most interesting man in tennis."

Much to his dismay, he's far from the best known man in tennis, primarily because he has been one of the most underachieving players in the sport over the past few years. However, there are signs that the racket-smashing Gulbis, who is the son of one of the wealthiest families in Latvia and has joked (presumably) with the press about owning "a helicopter, a submarine, and a spaceship," is finally ready to live up to his potential as a top tennis player.

Gulbis burst onto the tennis scene six years ago at the 2008 French Open, advancing all the way to the quarterfinals as a teenager before losing to Djokovic in three tight sets. His future seemed impossibly bright at the time. However, he failed to make it back to a major quarterfinal until this very tournament. In the past six years he has lost in the first round of 10 majors, the second round of 10 majors, missed two majors, and only advanced to the third round once. For a player with six career titles and an array of shots that most top 10 players can only dream about, this was an inexcusable squandering of talent.

Throughout this time, Gulbis grew famous in tennis circles for his off-court hijinks, head-scratching results, occasional surprise runs through smaller tournaments, and, most notably, his tell-all interviews. Without the pressure being politically correct for sponsors or a reason to fear controversy of any kind, Gulbis's overly honest and bemusing interview became more famous than his forehand. It was a strange period.

In 2009, Gulbis went through nine months of the year without winning back-to-back matches. At a tournament in Sweden that fall, he was jailed for one night under the suspicion of soliciting a prostitute. He blamed the Swedish police, but was unashamed and considered the experience a feather in his cap. "It was very funny," he said later. "I think every person should go to jail once."

In 2010, the Latvian showed flashes of on-court brilliance, winning a small tournament in Delray Beach and making the semifinals of the Masters Series event in Rome, taking out Roger Federer along the way. In his win over Federer, he squandered six match points before clinching the win. "You know, there's a good expression in English but it involves bad words," he said after the match. "So I'm not gonna say it. I … did it in my pants."

At the 2012 Winston Salem Open, I talked with a frustrated Gulbis about his up and down career so far. "I just prove to myself that when I'm good I can beat anybody. It's clear for the rest of the players as well. They know when I play well I will give them trouble. Doesn't matter who it is. When I play bad, I can lose to anyone," he said. "I really get pissed off if I am playing like shit, like I did at the beginning of the year, I didn't get any wins. It's a joke."

He also complained about the quality of the opponents ranked ahead of him. "No disrespect to the other guys, but when I see what kind of players are already in top 50, I'm a bit shocked. I don't know some of the names."

By the end of that year, Gulbis had plummeted all the way down to No. 159 in the rankings. He had to miss the 2013 Australian Open because he didn't qualify for the main draw, and when he fell early in a couple of European Challenger events (the equivalent of the minor leagues in tennis), his mother suggested that he quit the sport altogether.

"I told her, 'Give me one more month,'" he said.

The month paid off. Gulbis went all the way through the qualification rounds to win the Delray Beach International Tennis Championships in February. That launched him safely back into the top 100, and he was able to continue building on that success in the smaller tournaments throughout the year. 

Gulbis has continued to forge ahead in 2014, showing surprising consistency week in and week out. He already has five top-10 wins this season, and he's notched 32 victories with two titles. Perhaps most impressively, out of his 10 losses this year, only two have come to lower-ranked players. Thanks to his great showing at Roland Garros this year, he will be in the top 10 for the first time in his career when the tournament is over.

So what's the secret? Well, simply put, Gulbis finally grew up. After winning his title in Delray Beach last year, Gulbis announced that he'd made some positive changes. "I quit a lot of stuff in my life," he said. "For example, smoking, drinking, staying up late."

He's been working with his coach Gunther Bresnik for a couple of years now, and, according to what he told the French Open media, Gulbis has been taking their partnership seriously:

"[Bresnik] didn't deal with those kind of problems which my other coaches were dealing with three or four years ago. I missed a practice once with Gunter because I had a long night. I called him at 7 a.m., and I said, 'Gun, I cannot come to practice.' He understood it. It was once.

"With other coaches, the first time when Hernan Gumy came to Latvia to prepare for Davis Cup; eight days of preparation, I missed five days of practice.

"And then you evolve, you start to understand, Okay, first, make one step. Don't miss five days of practice. Just miss three days of practice and then two days and then one and then nothing. It's a process."

It's impossible to deny that it's good to have a player like Gulbis having success, both because he has the talent to beat anyone and because he has a very different personality than other players on the tour. You'd be hard pressed to find another tennis player who can coherently talk about Dostoyevsky, Murakami, Kanye West, and opera all in one interview, and Floyd Mayweather and beer in another

Still, with a guy like Gulbis, there's rarely a lack of controversy. He made headlines during the first week of Roland Garros when he said that he hoped his sisters didn't become tennis players because, "A woman needs to enjoy life a little bit more. Needs to think about family, needs to think about kids."

While his social views and refined tastes might not be everyone's cup of tea, Gulbis surely succeeds at keeping the world of men's tennis from being too boring. Of course, it helps that he's finally going deep into tournaments again.

The engaging and enigmatic Ernests will play Djokovic on Friday for a spot in the French Open final, and while he'll certainly be the underdog, it'd be foolish to overlook him. With his wacky, crossing-guard forehand, powerful serve, and ability to hit winners from anywhere on the court, Gulbis could just be the guy to break up the predictability at the top of the men's game. After all, he's finally decided that winning tennis matches is what makes him happy.

"So for me it's really important for my happiness just to be successful on the tennis court," he said after his emphatic win over Berdych. "Forget about the money. Forget about fame. It's just about my inner comfort. That's it. For me, that's all that matters in the end of the day."

It's a good thing that Gulbis didn't listen to his mother last year when she told him to leave the sport behind.

"Now she tells me if I win [this year's French Open] I shouldn't quit." 

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Lindsay Gibbs is a freelance writer, tennis lover and author of "Titanic: The Tennis Story." She is a co-founder of The Changeover and can always be found @linzsports.