Spaniard Sergio Garcia (68), who had his girlfriend, Katharina Boehm as the caddie this week, held off World No. 3 Henrik Stenson (68) to win his first title of 2013.
Garcia finished at 22-under 266 and stayed four clear of Stenson, winner of the FedEx Cup and Race to Dubai on either side of the Atlantic this year. Stenson was 18-under 270.
Lahiri finished at 13-under 275, nine behind Garcia, but he was the top Asian Tour player.
Gaganjeet Bhullar (70) was steady with four birdies and two bogeys to tie for 10th with Thongchai Jaidee (68) and Marcus Fraser (69) at 10-under 278.
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Sujjan Singh (75), tied seventh overnight, had a sharp fall to tied 30th, where he was in 2012 Masters winner, Bubba Watson's company. Sujjan roller-coaster ride had two doubles, four bogeys and five birdies.
Jeev Milkha Singh (69) with six birdies and three bogeys, shot his best round of the week and moved up to tied 36th at four-under 284.