World number six Disi clocked one hour and 43 seconds while Alemu, ranked 10th in the world, took one hour, 10 minutes and 30 seconds to travel the distance of 21 km.
Disi took home the winner’s purse of $20,000 while Alemu was richer by $18,500.
Kenya’s Isaac Macharia (60:47) and Tanzania’s Dixon Marwah (62:02) followed Disi in second and third places respectively.
The Kenyan duo of Patrick Mbuvi and world number three Wilson Kiprotich finished fourth and fifth respectively in a photo finish after both clocked 62:03.
Alemu, meanwhile, was followed home by compatriot Atsede Habtambu, who clocked 1:10:36. Kenya’s Kenya’s Alice Timbill came third in a time of 1:10:40.
The Indians in the fray also improved their performances, with last year’s top finisher Ram Singh Yadav once again being the local champion while ending up 16th this time.
Yadav clocked 1:06:09 to finish a rung ahead of Deep Chand, who missed out on becoming the Indian champion by just a second to end 17th. Mukesh Kumar was third among Indians in a time of 1:06:12, and 18th overall.
Kavita Raut was the new Indian women’s champion as last year’s champion Pampa Chanda failed to even make the top-20. Kavita finished 15th overall with a timing of 1:18:34.
Disi and Macharia were going neck and neck before the Rwandan sprinted off in the final kilometre to emerge a clear winner. Macahria said he was happy to finish runner-up as he was not even in a very good position when it started.
The women’s race was also a close affair until the final 200 meters, when Alemu left her compatriot Habtambu behind.
“I came here for the first time and it’s been a great experience. The crowd support was fantastic,” Alemu said.
Yadav said the new route suited the Indians and helped them better their timing of the previous year.
The 22-year-old Kavita was running her maiden half marathon and had not even prepared for the event. “I am a track runner and my events are 5,000M and 10,000M.
“I have no idea how one prepares for a marathon but decided to give it a shot after hearing of it,” she said.
L Preethi Rao was second among Indians at 19th after clocking 1:20:38, while Vaishali Chatare was the local number three, finishing an overall 20th with a timing of 1:21:58.
Meanwhile, Rajiv Virat won the 4.3km Wheelchair Run, while Royal Bank of Scotland captured the Corporate Sporting Challenge trophy.