Arjuna always regarded Lord Krishna as divine and was very humble and obedient to him. He considered his friendship with him as his fortune.
Every warriors was defeated a few times except Arjuna. So Arjuna was equally unstoppable in Kurukshetra war. Only 1 instances came in whole 18 days war when he had down moment. Against Karna’’s Ashwasen’s arrow. But Shri Krishna intervened, just like Ashvatthama saved Karna from Arjuna.