Every year, a few promising players appear on the ATP Tour and at least on occasion they show flashes of brilliance, which is why they are tabbed as players to watch.

But with tennis’ Big 4 of Roger Federer, Novak Djokovic, Rafael Nadal and Andy Murray lapping up every major title, it’s possible that the current younger set of males may never become top 5 players or make major impacts on the tour, which means, by the way, winning Grand Slams, Masters Series titles or Olympic gold medals.

The current group most closely watched includes Canadian Milos Raonic, Australian Bernard Tomic, American Ryan Harrison and Bulgaria’s Grigor Dimitrov, all of whom are 21 and under. None have reached the quarterfinals of a Grand Slam yet or the semifinals of Masters Series. Only two – Raonic and Tomic -- have won titles. 

Two years from now they could be facing off Grand Slam finals like the current Big 4 is. Or they could still be struggling to crack the top 10 and consistently losing to the elderly elite players. That what makes the sport fascinating to fans, and can given the observed players heartburn.

"Anything is possible, right? They could all be No. 1 in the world at one point or they could never be in the top 5," Federer told me at the Western &Southern Open  in Cincinnati when I asked him to assess the new generation. "We don't know right now. I hope they will make it far and go deep in big tournaments and reach very high in the rankings."

He hopes so, as long as they don't beat him in the process. Federer is sort of late bloomer, at least by Nadal standards (the Spaniard won his first major at 19), as he didn't win his first major until he was 21 at 2003 Wimbledon, and he was just a month shy of his 22nd birthday. Federer was already a top 5 player before he won Wimbledon and he won eight titles. He would win 16 more majors over the next nine years and is still going strong.

But when Federer began to make his breakthrough, he was very close in ability to the elite players of his generation. So was Nadal, as proven by his excellent record against Federer, So was Djokovic whose head to head against the rest of the Big 4 is more than respectable. The same could be said of Murray, with the exception of his record against Nadal.

None of the new generation is that close to the Big 4 now.

"We’ve got a ways to go," said the 20-year-old Harrison, who is ranked just inside the top 60. “There are so many steps. Once you start beating those guys in the top 10 you have to do it consistently. And they have such a stranglehold on the tour it’s a ways to go. The way you get to that level is to keep pushing each other, keep working and trying to improve."

Federer isn’t sure, even if he can see their talent. Raonic is the most ‘proven’ commodity, having already cracked the top 20. He reached the quarterfinals of his home country tournament in Toronto last week and took a disappointing loss to John Isner. On Tuesday in Cincinnati he scored a big win over Toronto finalist Richard Gasquet. He has a huge serve, big groundies and can volley fairly well, but his movement and return game are still suspect.

"There is always a window. It's just a matter of exercising it," he said. “I have had the issue that I have seen sort of openings in the window, but I have sort of just been like sliding it open slowly.  I just need to sort of kick through and go for it and just try to make the most of it.”

The tall and agile Tomic is a super creative hard-to-read player, but he is enigmatic and doesn't always work hard enough. The 19-year-old former Australian and Wimbledon quarterfinalist who this week in Cincinnati has bested Harrison and Brian Baker after a pretty lousy summer said he'd love to put himself and the other three amongst the top “but we are in the most difficult time of tennis and the top three to four show they are legends. Ten years ago, 20 players could win a Grand Slam. Now there are just three players and Murray’s still struggling and it's a difficult time for young players. But if we improve. I think our time will come in the next few years.”

Dimitrov has a colorful game but is a bit of head case and can’t put consistent results together. Harrison is ultracompetitive but still hasn't figured out which game style best suits him and he wants so badly to be successful that he is capable of driving himself into the ground. He is in the midst of a three-match losing streak with his nation’s biggest tournament just around the bend at the US Open.

"I wrote him the other day, said one of his mentors, Andy Roddick. "I said, 'Everyone has great character when they're winning. This is the time to test it and see where you’re at.' You're supposed to be frustrated. That's the way it works. He works hard. If anything, he almost wants it too bad sometimes. He'll figure it out, though."

After his loss to Tomic in Cincinnati, an upset Harrison approached Fish in the parking lot. He’s very keen on receiving advice, but as smart as he is, he could use a little more of Federer’s cooler head and Djokovic’s unerring consistency.

"He's struggling with his confidence a little,” Fish said. “Every single tennis player has been there. It's an unbelievably tough mental sport, and when you struggle with it, it's hard. Obviously he has some demons there that he needs to tame at times. I'm sure he'll be the first to tell you. We all have demons that sometimes come out at bad times and times when you're struggling mentally. I just said, ‘Sometimes when you're not hitting the ball well you need to try to rely on things that you can handle: Fitness, the mental side of the game…He wants it. I don't think it's a bad thing that you want it bad enough. It might hurt you at times, but that's going to pay off in the long run.”

Federer has a very interesting perspective on the subject, saying that part of what moved him from a very good player to become great player was the pressure of having to show that he was worthy of being mentioned in the same breath as the other elite. No one can possibly do that with any member of this generation, not until one of them wins a Masters Series or makes a very deep run at a Slam. They can be talked about, but it’s mostly speculation.

“I had [Lleyton] Hewitt and [Marat] Safin and Roddick and Ferrero and all these guys were almost a touch better than me while I was coming up,” Federer said. "I was being compared to [Pete] Sampras at the same time. I didn't have basically any titles, any Grand Slams. So I guess that was a key for me of trying to become a better player, understanding that I need to improve if I want to keep up with these guys. Then I would beat them from time to time, I would lose from time to time, but I would learn a lot. For them, they're not quite being compared to the same age. Grand Slam champions, yeah, because it's hard to compare them to us right now because we're older than all of those guys. But it's an interesting phase for them I think in their career right now because I'm sure they're going through some ups and downs as well emotionally.”

Federer added that at times he felt like he was going to make a big break though and didn't and he grew frustrated. He didn't like to practice as he’s more of match player, but he did so anyway because he realized it was crucial to his success.

The superstars live in sort of bubble and until the younger set actually begins to beat them, they are not going to be considered surefire elite. That's the way it goes in the locker room and is a fair way of looking at things. If one or all of them make a move at Cincinnati or the US Open, then they will legitimately be in the conversation.

Federer believes that they will learn and become great players.

At the very least they are worthy of notice, right Roger?

“ I guess [since] you mentioned them they are expected to get in the top 10 in the next few years,” he said.

Like Federer, I guess I expect that too, but like Raonic, I’d like to see the younger set kick in the window a little faster.