Sasuke was knocked down but not unconscious. One don't go from being unconscious to back on there feet in literally 4 seconds.
Concern=/= fear.
Sasuke lead the way the entire fight.. Only time Naruto had the lead was when he use Kruama's avatar.
It's a proven fact that Sasuke was unconscious, he wasn't moving at all. He later woke up after the red chakra appeared and you know the rest of the story.
Not sure what you mean lead the fight, you should probably watch it again. They were both running at Momoshiki at the same time, they both landed their hits at the same time, and then they began to fight in a cooperative pace.
No one was leading that fight. You could say Naruto took charge a bit after Sasuke was blasted to an unconscious state and began to destroy Momoshiki's Wood dragons, and Phoenix. But then Sasuke woke up and with their combined efforts they took down Momoshiki's Lava/Earth Golem together.
Afterwards Naruto enhanced Boruto's Rasengan, and then Boruto/Sasuke worked in a synchronized pace to bring down Momoshiki with the Father/Son Rasengan.
Overall there was no leader, it was an even pace between each shinobi.
Excluding the Kage's who helped too but they don't factor in the long run.
Sasuke couldn't even hold it for 2secs lol and Naruto kept on going Momo had to pull out two blades to battle against him. Landed a monster punch! remember they trying to nerf this guy he could dominate in a second. He was the reason Sasuke was able to grab and kick momo a couple of times. Remember Naruto was the one that grabbed him first.
