The Mavericks won their third in a row as they try to fight their back to a playoff berth.
New Orleans took a 100-96 lead on a 3-pointer by Ryan Anderson with 55 seconds remaining and the Hornets did not score again.
James, who had played with 11 different NBA teams before signing with the Mavericks, kicked off the late comeback and Vince Carter put Dallas in front by hitting a 3-pointer with 6 seconds remaining.
Dirk Nowitzki scored 25 points for Dallas and Carter added 22. Gordon led the Hornets with 23 points.
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