World number one Rafael Nadal remains conscious of the threat posed by Juan Martin del Potro, despite evading a US Open semi-final meeting with Roger Federer. The Spaniard soared into the last four at Flushing Meadows for the fifth time after quickly dispatching Russian Andrey Rublev, but instead of booking a 38th career clash with Federer will instead take on the 2009 champion Del Potro.

The Olympic silver medallist rolled back time – having beaten Federer in the final eight years ago – to overcome the Swiss in four sets and reach the semi-finals for the first time since he won the title.

Despite having been dogged by wrist injuries since claiming his only grand slam title, Del Potro has won each of the last two meetings with Nadal, including at last year's Rio Games when he ousted the 10-time French Open champion in a three-set thriller. Del Potro has recaptured some of his best form en route to the latter stages and Nadal is well aware of the threat he poses.

"Juan Martin is a top player, no? Is true that when he's playing well, it's difficult to stop him," he told reporters. "Probably the forehand is maybe the fastest on the tour. If he serves well and hit well his forehand, he's a player that has the chance to win against everybody.

"Of course I have to play my best tennis. I need to be very focused with my serve and play aggressive, because if you let him play from good positions with his forehand, you are dead, because he plays super-aggressive, hitting so hard.

"So probably he's unstoppable from that positions, no? I need to play long, I need to play against his backhand, and then open the court, no?

"These kind of matches, we can talk about things. Doesn't matter if it's Roger or Juan Martin. The end of the day, we can be thinking or talking about what I have to do or what I don't have to do. Sport is not that difficult. The player who plays better that day is the player that is gonna have better chances.

"Then there are small adjustments, if you can do it. But the most important thing is to play at my best level. If I play at my best level, I believe I am gonna have my chances against everybody. If I don't play at my best level, the chances will be much less."

Juan Martin del Potro and Rafael Nadal
Del Potro has prevailed in his last two meetings with Nadal - including at last year's US Open. Getty Images