Tobi (Obito) intercepts the Leaf Village search party (Naruto, Kakashi, Hinata, etc.), using his intangibility to stall them and prevent them from reaching Sasuke.
Fans often discuss this episode as the "calm before the storm," contrasting Sasuke's cold determination with the Leaf's desperate search. Naruto Shippuden Episode 134
Kakashi notices Tobi has a Sharingan during their brief skirmish, a major revelation for the Leaf ninja. Tobi (Obito) intercepts the Leaf Village search party
Watch a detailed reaction and breakdown of the events leading up to the Uchiha brothers' fated battle: Naruto Shippuden Episode 134