(CNN) -- After a difficult past year, Rafael Nadal is back where he feels most comfortable -- but his rivals are battling to find form ahead of the French Open. 

While the Spaniard cruised into the quarterfinals of the Monte Carlo tournament he has won for the past eight seasons, world No. 1 Novak Djokovic again had to come from behind to earn his place while Andy Murray suffered a crushing defeat that will demote him to third in the rankings. 

Fourth seed Tomas Berdych and No. 5 Juan Martin del Potro also crashed out Thursday to thin out the competition for Nadal as he continues his winning return to the ATP Tour following longterm knee problems. 

His 6-2 6-4 rout of German 16th seed Philipp Kohlschreiber was his 16th successive victory this year following a defeat in the final of his comeback event in Chile in February. 

"I feel more relaxed, yes. I had some uneasy moments during the past year," Nadal said after his 44th consecutive win at the clay-court event, which set up a clash with 21-year-old Bulgarian Gregor Dimitrov. 

"Now I'm back on the tour. Just being here is good news. And winning matches -- I say it every day, but winning every match is very important to me today. Every time I have the chance to go on court and play well, feel competitive, is a really good feeling." 

Dimitrov is also on a roll, having followed up his opening victory over world No. 10 Janko Tipsarevic by beating Germany's Florian Mayer 6-2 6-4.  QUESTIONS:

Q1:
1. Who is currently seeded fourth?
2. Who has three people in front of him in the seeding?
3. What is the name of the player that is seeded fourth?
Q2:
1. Where is Juan Martin del Potro's seeded?
2. What seed does Juan Martin del Potro have?
3. What is Juan Martin del Potro's seed number?
Q3:
1. Who has returned to his comfort zone?
2. Who is back in his regular spot?
3. Who has come back to a place he feels at home in?
