Nadal puts the loss down to the misfortune of facing an inspired opponent.
"I prefer to win all the matches. Not just before Wimbledon, I prefer to win all the matches of the year.
"It's nothing very negative. I won a tournament last week and, this week, I lost an opportunity."
Unlike Nadal, three-time champion Andy Murray had no problems at Queen's as he saw off Taiwanese qualifier Lu Yen-Hsun 6-4 7-5.
French champion Stanislas Wawrinka triumphed 6-3 6-4 over Australian rising star Nick Kyrgios. The Swiss second seed will next face South African Kevin Anderson.
Defending Queen's champion Grigor Dimitrov moved into the second round to face Gilles Muller, after a 4-6 6-3 6-4 victory against 2010 winner Sam Querrey.
- AAP