''I have never played so well on grass,'' said the second seed, who will meet seventh-seeded Czech Tomas Berdych in the last eight tomorrow.
Nadal, runner-up last year, struggled to find his rhythm for two sets after his third-round match against Swede Robin Soderling, a five-setter which was on the Saturday schedule but did not conclude until yesterday.
Youzhny initially played near flawless tennis, finding the corners and hitting fine volleys at the net, before being hampered by a long-standing back problem.
''Another line'', Nadal cursed under his breath after an ace from Youzhny in the second set, a resigned reaction to the precision in the Russian's game.
Youzhny, who had twice beaten Nadal in the last 12 months, took the first set on his first break point of the match after a rare double fault from the Spaniard and broke again two games into the second after a superb backhand crosscourt winner.
ROLE REVERSAL The roles were dramatically reversed from the start of the third set which Nadal raced through in 27 minutes after breaking Youzhny to go 2-0 up.
The Russian, who pulled out of last month's Halle tournament with a back problem, then asked for courtside treatment.
''Throughout the third set I thought about calling for the physio... but that would have been a motivation for Nadal,'' the 14th seed told a news conference.
''It's tough, because it looks like I can do everything but I couldn't move like I did in the first and second sets,'' added Youzhny, who could no longer chase every Nadal effort with the same vigour as he had done early in the match.
There was the threat of a rain interruption when the score was 1-1 and 30-30 in the fourth set but it did not materialise and Youzhny again asked for the physiotherapist in the break when Nadal led 3-2.
''The key was my determination. I was more aggressive,'' said Nadal, whose turn it had become to find the corners with almost monotonous regularity, also notching up a match tally of 11 aces while Youzhny won only two more games.
REUTERS SY HS2150