Nadal takes on Pella for the second time in his career while looking to progress to the third round at Roland Garros.
The world No 1 was far from his best when he beat Simone Bolelli in straight sets in round one.
But Pella thinks the Spaniard will still be too difficult to face even if he is not on the top of his game.
The pair’s only previous meeting came at Indian Wells last year which Nadal won comfortably.
And Pella is fearing a reunion and ruled out any hopes of getting a result.