The second seed Somdev came back from the brink to subdue Japanese rival with a 6-2, 0-6, 6-3 triumph and ensured the country at least of a silver in the men's singles, which would be a first for the country.
Top woman player Sania Mirza had won a silver in 2006 in Doha in singles but no Indian before Somdev has reached the gold medal round in men's singles.
India has won three bronze medals in men's singles so far. Leander Paes had won it in 1994 in Hiroshima Games and Mahesh Bhupathi and Prahlad Srinath had won it during 1998 Games in Bangkok.
In the baseline slugfest, that lasted almost two hours, second seed Somdev pocketed the opening set against Ito, ranked 195, with a measure of comfort but was then blown off the court by the fourth seed Ito, who clinched the second 6-0.
Things were looking difficult for the Indian world no. 106 when he and his rival traded service breaks in the first four games. Somdev then staged an excellent rally under pressure by saving two break points in the fifth game.
That was the turning point as Somdev regained poise and broke his rival for the third time, this time decisively, before taking the set 6-3 and reaching the gold medal round where he will face top seed Denis Istomin of Uzbekistan.
Istomin was too good for third-seeded Japanese opponent Go Soeda and completed a facile 6-1, 6-0 victory.
After saving two break points and facing a third, Somdev came up with an attacking forehand lob at full stretch from the corner that sailed over the Japanese waiting for the kill on the other side and landed just inside the baseline.
From that stage on, the Indian was on song as he held serve for a 3-2 lead and then broke his rival immediately to make it 4-2 with an excellent return of serve that was netted by Ito.
Later he told reporters that the fifth game when he was down and out was the turning point.
"It was a great match. I just hung in there, saved the break points in the fifth game and held on to my serve," he said.
Somdev, who played his 13th match in the tournament as he is competing in men's doubles event also, said the packed schedule was not a problem.
"I have done it before, playing the Challenger and the Davis Cup. And I am not traveling here and my physical trainer is there," said the 24-year-old Somdev.
Istomin said he expected a tough battle in tomorrow's final against Somdev.
"I have played against Somdev a couple of times before. He is very tough," said the Uzbek top seed.