Novak Djokovic said his first-round win over Kei Nishikori at the Madrid Open was "exactly" what he needed for his confidence after a run of poor form.
The 30-year-old former world number one has failed to reach the quarter-finals in five tournaments since returning from elbow surgery in January.
But he impressed in beating Nishikori 7-5 6-4 to set up a potential second-round tie with Britain's Kyle Edmund.
"It was exactly what I needed for my confidence," said the Serbian.
The 12-time Grand Slam champion, now ranked 12th in the world, said earlier this month that his confidence had been knocked by making a premature return two months after surgery.