Juan Martin del Potro was hitting tweener lobs before they were a trend on the ATP tour. As a lanky 18-year-old, Del Potro showed off his swag against Tommy Robredo in Madrid back in 2007.

Despite losing the first set, the Argentine rallied to a three-set win before falling in the round of 16. Del Potro was ranked just outside the Top 50 then, yet just two years later, he would win the US Open.

Going into Madrid this year, Del Potro, now 29, is ranked No. 6. He hasn't played since the Miami Open, where he reached the semifinals after winning Indian Wells.

Advertising

Flashback: Del Potro
hits insane tweener 
as teen in Madrid

Flashback: Del Potro hits insane tweener as teen in Madrid

Coverage begins on Tennis Channel and Tennis Channel Plus on Sunday