Seven-time French Open champion Rafael Nadal admitted on Wednesday that he is wary of history repeating itself when he returns to the grass courts of Halle for the first time in seven years on Thursday.
Nadal has played this pre-Wimbledon just once, in 2005, arriving in Germany on the back of his first Roland Garros title.
But his career grasscourt bow was brief when he lost in three sets to Germany's Alexander Waske in his opening match, a defeat that did little to boost his confidence on what was then an alien surface.
"When you win a tournament like Roland Garros, it's very difficult to play the following week. Especially when you win for the first time, the first Grand Slam in my career," said the world number two.
"This time, I can lose tomorrow (his singles opener against Slovakia's Lukas Lacko) but for sure I'll try to stay focused on the match."
Since that 2005 setback, Nadal has mastered grass courts, winning Wimbledon in 2008 and 2010, two of his 11 Grand Slam titles which were boosted to 11 in total by his record-breaking seventh French Open victory on Monday.
"The week after winning a tournament like Roland Garros is never easy because there is a lot of tension, a lot of emotion," said the Spaniard.
"I also played a lot of matches on clay this season, I am always a little tired after the French. There are adjustments -- the speed of the court, how to hit the ball on grass.
"I came here in 2005, played a couple years at Queen's, the transition was never easy. A tournament after the French Open, you have to be very careful because the first round can be very dangerous against any player.
"This is the most drastic change in the season, makes success here very difficult."
Nadal added that long-time rival Roger Federer, a five-time champion in Halle, and the second seed this year behind the Spaniard, will be the favourite for a sixth trophy.
He believes Federer masters the quick switch from clay to grass better than most players.
"He's a specialist. I did pretty well the last few years, winning Wimbledon and Queen's. But for Roger, the transition from clay to grass is easier than for me, it takes less time," he said.
"I need a period of time, spend hours on the court to compete. Every match I'll play here will work for me. I'll try to play the most hours I can."