The story of Arjuna's chariot moving backwards by two steps when Karna's arrows hit and Sri Krishna applauding him, does not find place in Mahabharata.
However, the following incidents did take place, which can be credited to Karna's valour.
1. Karna's arrow misses Arjuna's head due to Sri Krishna's intervention.
The Suta's son then fixed on his bow-...