Congrats, Grigor Dimitrov, but what's next?

For so long, it seemed Grigor Dimitrov never got his substantial tool box organized. He lacked the commitment of an elite player, and unless he was on a hot streak, riding his ball-striking talent, he was vulnerable, volatile and prone to frustration.

But the 26-year-old Bulgarian with the stylish game is catching up with the hype that has trailed him since his teenage years, when he was dubbed "Baby Fed."

On Sunday in London, he won the ATP World Tour Finals, the biggest title of his career, by outdueling David Goffin 7-5, 4-6, 6-3 in a tense, 2½-hour match. It was an emotional, enervating triumph that left Dimitrov somewhat speechless.

"I'm lost for words a little bit, I'm not gonna lie," Dimitrov said when he was presented with the trophy. "I'm usually pretty good at this."

Now the question is as simple as the answer is complicated: Can he make up for lost time?

First, we have to look at the competition atop the game. Swiss icon Roger Federer is approaching 37, and Rafael Nadal, although the top-ranked player this season, is once again dealing with knee troubles. The picture at the top of the men's game seems more clouded than it has been in a decade, especially with the string of injuries that hit the tour this season. Four of the top five players from a year ago never lasted long enough this season to make it to the top in London.

So it seems Dimitrov is positioned to wedge himself more deeply into the Grand Slam conversation than ever before. The intriguing detail is that Dimitrov, who will finish the year ranked No. 3 behind Nadal and Federer, has threatened to be a force at the top before only to slide back.

He was the world's top-ranked junior a decade ago, sweeping the boys' titles at Wimbledon and the US Open. He was a Wimbledon semifinalist in 2014, the year he hit a then-career-high ranking of No. 8 at age 22. But he stumbled, falling as far No. 40 by the summer of 2016.

"Reaching No. 8 in the world at 22 was a difficult learning experience for him," Dani Vallverdu, Dimitrov's coach since August 2016, said at the Miami Open last February. "But it was good for him. Our main priority now is to keep things simple."

Simple is exactly what Dimitrov needs. He has never been easy to coach. Look no further than the string of six individuals who have worked with him.

The two faces of Dimitrov were on display over the weekend in London. During Saturday semifinals, it was almost painful to watch as he struggled with his nerves, trying to close out Jack Sock. But Dimitrov showed grit and survived.

In the final Sunday, he played brilliantly to reach triple-match point with Goffin serving down 5-2, only to see the calmer Belgian pull out the game with some brilliant shot-making. But Goffin's fightback didn't rattle Dimitrov. Pausing now and then for a deep breath, he played an excellent service game to win the title.

At 26, he's in the prime of his career. But he's also one of a number of players, including Goffin, Kei Nishikori, Sock and Milos Raonic who have been suppressed by the continuing excellence of Federer and his Big Four compatriots when healthy. Dimitrov and the outsiders are at about the midpoint of their careers and none has tasted ultimate success at a major.

But what's the rush? Look around the men's tennis landscape and this has become a game dominating by older players. We already know what Federer and Nadal did this season, winning two majors each. Novak Djokovic and Murray each hit 30 years old. And let's not forget Stan Wawrinka, Tomas Berdych, David Ferrer and Jo-Wilfried Tsonga. They are all consistent top performers who are in their fourth decade.

This was the eighth -- and by far most significant -- title of Dimitrov's career. He raked in half of those trophies this year, including Cincinnati Masters, which he won in August. That was his first Masters 1000 championship. Still, Dimitrov has a lot of ground to make up if he hopes to rise above the good to the great.

As ESPN analyst Brad Gilbert said after the match, there's not a lot that separates the No. 25th-ranked player from No. 3, so if Dimitrov is going to maintain his lofty position, any small shortcoming will hurt. But Gilbert also said that it's now time to start talking about Dimitrov in the Grand Slam picture. Australia, anyone?

On Sunday evening, Dimitrov sounded like a player who might have figured out how to stay near the top of his game and the rankings.

"This makes me even more locked in, more excited about my work and for what's to come," he told reporters. "I know what I have to do in order to do good."

It's a valuable lesson to learn the second time around.