The 27-year-old is now second in the list of players with the longest unbeaten record for their teams in Liga history.
Real Madrid legend Emilio Butragueno holds the record after playing 50 league games for los Blancos without suffering a defeat.
The win over Sporting means Iniesta overtakes Chendo, another former Madrid player, whose tally stands at 47.
Iniesta and his team-mates will now prepare for their Champions League round of 16 second-leg fixture against Bayer Leverkusen on Wednesday, taking a 3-1 lead into the game at Camp Nou.
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