Blake, 22, had been quicker in Saturday's 200m semi-finals, running 19.93secs, while Bolt won his heat in 20.26secs.
They are the fastest two men of all time over the distance and their battles are set to be one of the highlights of the London Games.
"I'll have to figure out what I did wrong and work on it," said Bolt.
"I can never be discouraged," Bolt continued. "I'm never worried until my coach gets worried. My coach isn't worried, so I'm OK."
His coach, Glen Mills, said he was confident Bolt would be at his peak again in time for the Olympics, which begin on 27 July.
"Usain has the experience, the ability, he has been there already," said Mills. "He might be a little off at the moment, but I'm sure when the time of delivery comes around, he'll be on top of his game."
Race winner Blake had only words of thanks for Bolt.
"He always gives me a lot of encouragement and tells me to keep coming to this race," said Blake.
"A lot of people gave me encouragement, said ' Yohan Blake, you can do it'. I just wanted to keep performing and keep going."