RPT-FEATURE-Tennis-Four titles make Del Potro an Open dark horse

(Repeats feature first moved at 0105 GMT)

NEW YORK, Aug 20 (Reuters) - Teenager Juan Martin Del Potro has emerged as the dark horse at next week's U.S. Open after a sudden flurry of success.

The 19-year-old Argentine has won 19 matches in a row and four titles in succession. At 17th in the world rankings, he is the only teenager inside the top 20.

At 1.98 metres tall, Del Potro is big but not huge by today's tennis standards. His stature in the game, though, is growing with every week.

His wins on clay in Stuttgart and Kitzbuehel and on hard courts in Los Angeles and Washington prove his versatility and his confidence has never been higher.

Nevertheless, the modest Argentine, who took this week off to give himself time to recover from his efforts, thinks he has a long way to go to be considered a real prospect at the grand-slam events.

"This year I will be seeded which is important," Del Potro told Reuters in an interview ahead of the Open, which starts on Monday.

GRAND SLAM