World number one Rafael Nadal admitted shock defeats to David Ferrer and Nicolas Almagro in recent weeks have shaken his confidence as he looks to defend his Madrid Masters title this week.
The 13-time Grand Slam champion has appeared almost unbeatable once he hits the red clay of Europe in recent years, but comes into Madrid having lost at the Monte Carlo Masters for only the third time in his career and for the first time at the Barcelona Open since 2003. (Related: Rafael Nadal looking to dispel doubts in Madrid Masters)
"Losing always creates doubts, anyone who tells you the opposite is lying," he said on Sunday.
"There is no benefit in losing. The easiest thing is to keep winning because everything comes naturally without thinking.
"When you lose you think more about where to move on the court, where to hit the ball, but that is what has happened and as I have said various times you cannot win in Monte Carlo or Barcelona 12 times.
"To lose twice in the quarter-finals is normal. Perhaps what has been abnormal is what has happened in recent years."
Nadal could even lose out on top spot in the rankings this week should he lose before the quarter-finals and Novak Djokovic win the title for a second time.
However, the Spaniard is hoping the energy of the home crowd will provoke a return to form.
"I feel a bit better and I am desperate to play in this tournament because it is always special for me. The energy this tournament gives me is a bit different and hopefully you will see that on court."
Wimbledon champion Andy Murray also returns to action in the Spanish capital this week after nearly a month off following Great Britain's Davis Cup defeat to Italy.
- Rankings boost -
The Scot has spent the time away from competitive action practising in Valencia and for a few days at Roland Garros ahead of the French Open later this month.
And the world number eight is hoping a good run in Madrid and next week in Rome will help secure a boost in the rankings ahead of the French Open and the defence of his Wimbledon crown.
"The most important thing now is that I show it on the court and at the major events. That's what I train for.
"Whether I can get back into the top four is something we'll obviously to have wait and see what happens over the next sort of six or seven months."
Murray is currently without a coach after his two-year partnership with Ivan Lendl came to an end in March. However, he is hopeful of making a decision on Lendl's successor before the start of the grasscourt season.
"I don't want to go into any names because that would cause me a lot of stress and questions over the next week or so, but it's something I did start to think about a lot the last couple of weeks.
"Hopefully I'm getting closer to making a decision in the next month or so."