Sasuke and Naruto's sparring match did not last very long. Although Naruto's growth was obvious and his strength had improved greatly, Jiraiya had still been too conservative in his teaching.
At present, Naruto was only slightly stronger than he had been at this point in the original story. This was because he had learned Wind Style ninjutsu while training with Yinsen before leaving the Hidden Leaf Village, had worked hard on his ninjutsu over the past two-plus years, and had developed greater tactical coordination between his Multiple Shadow Clones.
Other than that, there was Big Ball Rasengan, an advanced version of the Rasengan. However, it required two Shadow Clones working together to perform, and it lost the Rasengan's advantage of being quick and convenient to unleash.
Other than Naruto finally mastering the "correct" way to release the Rasengan, Yinsen could not see any fundamental change in Naruto's strength.
"You're being too conservative, Jiraiya!"
Before Jiraiya left, Yinsen had actually mentioned that Naruto should be allowed to properly master the Nine-Tails' power.
Clearly, Jiraiya had not taken his advice seriously. Or rather, he still regarded the Nine-Tails' power as a source of disaster and had Naruto suppress it as much as possible, even avoiding its use altogether.
"That power is too dangerous..."
Jiraiya knew what Yinsen meant, but he had personally experienced that terrifying power. He did not believe it could be controlled, and he worried that once it was released, Naruto would be consumed by the Nine-Tails.
"No power is absolutely safe. Was there no danger when Naruto trained in the Rasengan?"
If Naruto had not possessed an exceptionally tough constitution, the naturally robust physique of the Uzumaki clan combined with the special nature of being a Nine-Tails Jinchuriki, his method of training would have ruined his hands long ago.