Mumbai, Oct. 26 -- Karan Singh picked up his career's biggest title when he won the ITF M25 Mumbai Open on Sunday. The 23-year-old was leading 7-5, 3-1 when his opponent, compatriot Digvijay Pratap Singh, was forced to retire from the final at the MSLTA Courts. Playing in the heat, Digvijay struggled due to dehydration and vomited twice on the sidelines of the court before fainting. He was immediately taken to hospital, but returned to the court a few hours later for the prize distribution ceremony. Ranked 437 in the world, Karan was the third seed at the tournament in Mumbai. The title comes on the back of a decent run of form, in which he had reached the final of the ITF M25 event in Solapur last week. This was also his fourth title this year, having won two M15 titles in Bali and one M15 event in Hyderabad....