Del Potro in 2009 reached the semifinals of the French Open and then won the U.S. Open, the only player not named Roger Federer, Rafael Nadal, Novak Djokovic or Andy Murray to win a Grand Slam tournament since Marat Safin in the 2005 Australian Open.
But del Potro injured his wrist early in 2010 and his ranking, as high as No. 4, plummeted to No. 485 before he could play consistently again.
He's worked his way back to No. 8 going into a Wimbledon semifinal Friday against Djokovic, the world No. 1.
"I will need to be 100 percent or 110 percent against (Djokovic). He's the No. 1. He's a former champion here," del Potro after his quarterfinal win Wednesday. "It's going to be a more difficult match for me like today.
"But if I'm OK, if I do everything good to be ready for my next match, I will be excited to play against him."
If there is a question for del Potro's being ready, it's his left knee, which he injured in a third-round match. It also gave out in the first game in the quarterfinals.
Del Potro is just 3-8 lifetime versus Djokovic but he won their last meeting and took a straight-set decision in the 2012 Olympic bronze medal match, which was played at Wimbledon. It is their only meeting on a grass court.
Like del Potro, Djokovic is yet to lose a set this week. A win Friday would mark his ninth finals appearance in the last 12 Grand Slam events. He has the 2011 Wimbledon title among his six major tournament championships.
The other semifinal has second-seeded Andy Murray taking on No. 24-seeded Jerzy Janowicz, who is in his first Grand Slam semi. They have split their first two meetings but have never played on a grass court.
Murray is looking for a second trip to the Wimbledon title match. He lost last year to Federer in the finals. Overall he's 6-7 in major tournament semifinals, including 1-4 in the last five years at Wimbledon.
The British fans are also looking for Murray, who is from Scotland, to be the first British player to win at Wimbledon since Fred Perry in 1936.