“There was no way I was gonna lose this fight,” said Chiesa. “This is exactly what I wanted.
“There was no way I was gonna sell myself short. I overcame a lot of things,” added the 24-year-old, whose father lost his battle with leukemia two months ago.
Chiesa took Iaquinta to the mat with just two minutes on the clock, quickly taking the back of his team-mate, immobilizing him before clamping him with a rear-naked choke to secure the win after 2:47.
In the main event, welterweight contender Jake Ellenberger dominated Martin Kampmann for most of their fight before a right hook from the Danish striker, quickly followed by three knees, saw him snatch the win.
“I need to get punched a little bit to wake up,” said Kampmann, who has now won 11 of his last 15 bouts, including his last three in a row.
The victory is most likely to result in a bout with fellow top welterweight Johny Hendricks.
“I knew it was a tough fight coming in,” Ellenberger said. “He caught me and he had a better night. What can I do?”
Elsewhere in the event, 20-year-old Max Holloway, the youngest fighter in the UFC, secured a unanimous decision over Pat Schilling while Charles Oliveira beat TUF season 12 winner Jonathan Brookins with a guillotine choke in the second round.
Justin Lawrence provided the most dramatic end to a fight of the night when he knocked out John Cofer with a high leg kick just 20 seconds into the third round of their fight.
“This is just the beginning. KO of the year?” Lawrence said. “I’m happy with the KO but I’m not satisfied until I crack the top five. Then I’ll be happy.”
Other winners on the night included Myles Jury, with victory over Chris Saunders, and Daron Cruickshank, who secured a unanimous decision over Chris Tickle.
John Albert was controversially deemed to have submitted to Erik Perez in the opening fight of the night, putting his arm down on the mat to escape the tight armbar Perez had him in.