Flushing Meadows, NY (My Sportsbook) - The final quarterfinal bout at the U.S. Open was suspended shortly after midnight because of inclement weather with third-seeded Spaniard Rafael Nadal leading 11th-seeded Chilean Fernando Gonzalez 7-6 (7-4), 6-6.

Following the first set, there was a delay while Nadal received treatment for a nagging abdominal injury.

Nadal and Gonzalez then split the first four games in the second set before play was suspended 75 minutes because of rain. The sky cleared and the match resumed until the weather began to wreak havoc again, causing another stoppage with Nadal leading 3-2 in the second set tiebreak.

They are scheduled to continue play Friday afternoon, but more rain is in the forecast.

The winner of the match will face tall Argentine Juan Martin del Potro in the semifinals.

Earlier Thursday, the sixth-seeded del Potro came from behind to defeat 16th- seeded fellow 20-year-old and 6-foot-6 counterpart Marin Cilic 4-6, 6-3, 6-2, 6-1. Cilic stunned second-seeded and 2008 U.S. Open runner-up Andy Murray here on Tuesday and this marked his best-ever showing at a major.

Del Potro mounted his Day-11 comeback by breaking Cilic's serve to level the second set at 3-all. The big Argentine broke again for a 5-3 lead and then held to knot the bout at a set apiece.

In the third set, "Delpo" broke to open the stanza and notched yet another break for a 4-1 cushion on his way to another easy set win.

The fourth set was all del Potro, as he raced out to a 5-0 lead before crossing the finish line on his first match point in the seventh game of the stanza when Cilic launched one final forehand wide to give the Argentine his eighth break of the match.

Del Potro wound up winning 17 of the last 20 games in what turned out to be a rout after a tight first set. He moved on in 2 hours, 33 minutes, with the help of 53 unforced errors from Cilic.

"Was a good comeback, you know, the crowd cheering for me at 1-3 in the second," del Potro said. "I start to play better after that moment. Of course, I enjoy the match and I did good things. Of course, I need to improve for the semis a lot, but I'm happy with my match and with the result."

The ever-improving del Potro is now 2-0 lifetime against Cilic, with the other win coming at the Aussie Open back in January.

This marks del Potro's second trip into a Grand Slam final four, with the other coming at the French Open, where he succumbed to the great Roger Federer, back in June. He's trying to give Argentina its' first U.S. Open champ since the great Guillermo Vilas turned the trick in 1977.

"I had good experience here, some great matches, one comeback after being two sets to love down, and beating Murray also," Cilic said.

The other semi on Saturday will pit a top-ranked Federer against fourth-seeded Serbian star Novak Djokovic. The reigning Wimbledon, French Open and five-time U.S. Open champion Federer beat Djokovic in the final here two years ago. The 15-time major titlist Federer topped Britain's Murray in last year's title bout at the Billie Jean King USTA National Tennis Center.

The 2009 U.S. Open champion will pocket $1.6 million.