It is a funny thing about tennis – you can wait for years for something new and remarkable to happens and then, like London buses, two cracking stories come along at once.

As the US Open finally came to a conclusion – for the second year running, there was a rain delayed Monday final – there were two new champions and a small gaggle of new stars to admire.

Juan Martin Del Potro eventually stole the show by beating Roger Federer 3-6, 7-6, 4-6, 7-6, 6-2 to win his first grand slam title but he had to work awfully hard to knock Kim Clijsters off the front and back pages of the New York newspapers. Clijsters beat Caroline Wozniacki 7-5, 6-3 to win her second US Open trophy – but she did it after spending more than two years in retirement and in only her third tournament back on the road.

Del Potro did what no man had done before: he beat Rafael Nadal and Federer in consecutive matches at a major championship. He also managed to break the Swiss’s stranglehold on the tournament – no one had beaten Federer in New York since 2003 and the great man was attempting to win his sixth consecutive title there. Del Potro, all 6ft 6ins of him, put a stop to that.

The 20-year-old Argentine is a gentle giant. Softly spoken and almost apologetic in victory, he was stunned by what he had achieved. For a set and a half, he has been felled by nerves but then, just when all seemed lost, he earned a couple of break points and, although he failed to convert them, the very fact of having a chance shook the fear from his racket.

Federer, meanwhile, started off like a champion – even if his first serve stubbornly refused to cooperate – but ended up chasing shadows as Del Potro clattered his forehand and refused to give in. The longer it went on, the more fractious Federer became and as he raged Hawk-Eye (his least favourite invention in the world of tennis), so Del Potro concentrated even harder and just tried to play it point by point.

When, after more than four hours, it was over, Del Potro fell flat on his back and started to cry. He could not believe what he had just done and a week shy of his 21st birthday, he could not take it all in.

“When I lay down to the floor, many things come to my mind,” he said. “First my family and my friends and everything. I don't know how I can explain, because it's my dream. My dream done. It's over. I will go home with a trophy, and it's my best sensation ever in my life. It's too early to explain.  Maybe tomorrow, maybe next week I will be believing in this. But now, I don't know. I don't understand nothing.”

He earned an impressive $1.6million for his efforts which, when added to his bonus for finishing third in the US Open Series – the tournaments leading into the Open – brought his winnings to $1.85 million. So what was he going to spend his money on? “Some cheesecake for my birthday,” was all he could think of.

Clijsters, too was stunned by her success. She had happily walked off into retirement in 2007 thinking only of marrying her fiancé, Brian Lynch, and starting a family. When he daughter, Jada, was born 18 months ago, she was content, happy and completely satisfied with her lot.

And then the phone rang.

It was the All England Club asking her to take part in the test event on Centre Court in May, a jolly exhibition with Steffi Graf, Andre Agassi and Tim Henman to try out the new roof.

Determined to put on a good show, Clijsters started training. And the more she trained, the more she liked it. Perhaps she could do this more often. Perhaps she could play again. Perhaps she ought to try a comeback.

But never in her wildest dreams did Clijsters ever imagine that she could win another grand slam title, not after only two warm up events to test the water. Yet she ploughed through the draw, dropped only two sets and beat Venus and Serena Williams as she headed to the final.

Once there, she was tense and she was not playing her best but she was too experienced for Wozniacki. Unseeded, unranked and needing a wild card to get into the tournament, Clijsters became the first mother to win a major title in 29 years.

“I can't believe this happened,” Clijsters said. “Because it still seems so surreal that in my third tournament back I won my second grand slam. It wasn't in the plan. I just wanted to come here and get a feel for it all over again.”

“It's a great feeling to have but it's confusing in a lot of ways, as well. It went so quickly, everything. But it means the world, and I'm just so glad that I am able to share it with my husband and with our daughter, of course. It’s the greatest thing ever.”

Ah, yes, her daughter. While Mum dealt with all the post match details – on-court interviews, photographs and the like – Jada checked out the trophy, watched herself on the big screen at the back of the court, waved at the photographers and completed upstaged the new champion. All this and she is only 18-months-old. “She just thought it was the most normal thing, I guess,” Clijsters said with not a little hint of pride. “Brian and I were just talking to her and laughing with the way that she was handling it all.”

Then there was Wozniacki. At 19, she had quietly made her way up the rankings to No.8 by dint of winning more matches (62) than anyone else on the tour this year. It was her first grand slam final but judging by the way she enjoyed every moment of it, even in defeat, she will be back – as will Melanie Oudin, the woman she beat in the quarter-finals.

Oudin, from Marietta in Georgia, was the local favourite as she took out Elena Dementieva, Maria Sharapova and Nadia Petrova before running out of puff against Wozniacki. No matter, she is a fighter and at just 17, she should give the American crowds much to cheer in the future.

No, you cannot beat a good, heart-warming story and the US Open had them by the handful this year. It just makes you wonder how 2010 can top all of that.

Official US Open Website