Team USA Soccer has Mark McKenzie's back ... it released a statement Wednesday saying the racist trolls who spewed hate toward the USMNT player are NEVER welcome in the sport.
The org. stood up for the defender after he claimed that following the U.S.'s huge win over Mexico in the CONCACAF Nations League final in Denver on Sunday, he received tons of racist comments from fans online.
22-year-old McKenzie -- who struggled in the huge 3-2 win -- said the "racial abuse" and "personal attacks" were rampant .