Who left karna Midway in the war field when is Rath got stuck

In the Mahabharata, when Karna's chariot wheel got stuck in the mud during his final battle with Arjuna, Salya (also spelled Saliya) was his charioteer. Salya, who was actually the king of Madra and Arjuna's maternal uncle, had been forced to drive Karna's chariot against his will and had been demoralizing Karna throughout the battle. The question refers to this critical moment where Karna was left vulnerable.