Some dreams are worth waiting for.

For Angelique Kerber, who in the span of two days won her first US Open crown and became the new No. 1 in women’s tennis, at 28 the oldest to debut in the top spot, this had been a long time coming.

“When I was a kid, I was always dreaming to be number one and to win Grand Slams,” said an emotional Kerber on court after her victory.

Some athletes are pegged for greatness at an early age. They develop quickly and either fulfill their potential, or do not. It is rarer in professional tennis for someone to toil for years in relative obscurity and then suddenly explode with wild success.

That is what Angie Kerber has done.  

She was an almost complete unknown just five years ago at the US Open, already 23 and on tour for eight years, with few big results. A fan at the 2011 US Open, heading to then-new Court 17 to see an early-round match, was overheard saying, "Who's this Keebler person?" Little did she know that on that day she was about to watch not an elf, but a future No. 1.

The German turned professional in 2003, as a 15-year-old from Bremen. The first three years of her career were spent outside the Top 40. The first time Kerber made it past the third round at a major wasn’t until that 2011 US Open, when she reached the semifinal.

The late-maturing lefty made her rankings breakthrough in 2012, at age 24. She rose from 32nd in the world all the way up to No. 5. Yet her accomplishments at majors remained middling. Last year Kerber won five titles on tour, but she didn’t advance past the third round in any of the Slams.

This year has been wholly different. Two weeks after turning 28, Kerber began the year by capturing her first Slam crown at the Australian Open. The German overcame a match point against her in the opening round against Misaki Doi and went on to shock Serena Williams in the final. In her first Slam final appearance, Kerber had the fortitude to take the third set against perhaps the greatest fighter in history.

Kerber, though, was not the oldest player to win a first Slam title. Flavia Pennetta won the US Open at 33; Li Na and Francesca Schiavone were both 29 when they won the French Open; and Jana Novotna was just shy of 30 when she finally won Wimbledon in 1998.

However, none of those players ascended to No. 1 in the world.

After winning the Australian Open, Kerber admits that she went on a months-long walkabout, consumed by the immense pressure of being a Slam winner. But the feisty German found her way back to competition.

Kerber made the final at Wimbledon (where she lost to Serena); won a silver medal in singles at the Rio Olympics; and on Saturday seized her second Slam of the year (and of her career), beating the hottest player on tour in the last month, Karolina Pliskova -- winning five of the last six games in the third set.

“All the dreams came true this year,” exclaimed Kerber.

Age 28 probably doesn’t sound old to most people who aren’t professional tennis players, and it’s true that tennis is no longer a sport where teens rule – overachieving teenagers a notable rarity in late rounds of Slams these days.

But Kerber’s path to the top is just as rare.

To achieve her goals in Flushing Meadows was especially poignant for Kerber: “Everything started for me here in 2011,” she said, “and now five years later I’m standing here.”

Still standing. And now thriving.