Niyongabo, who has run the second-fastest 2,000 in 4:48.69, missed the World Championships in Athens last month with a stomach muscle injury.
The track in Rieti, a small town nestled in the mountains 35 miles north- east of Rome, has seen three records fall in the past five years, including the 3,000m mark Komen set last year.
Like Niyongabo, Komen was aiming at a record owned by Morceli: the 3:44.39 run by the Algerian at Rieti in 1993.
Morceli set the mile and 1500m standards on this track in 1992 and 1993 during his heyday as the world's premier middle-distance runner. He finished first in last night's 1500m, in 3:31.00, well outside his best-ever 3:27.37.
Kiptanui, the first man to break eight minutes in the 3,000 steeplechase and hoping to reclaim his record in the event, was within striking distance of the mark two-thirds of the way through but could not maintain the pace and clocked 8min 00.54sec. He was nearly five seconds outside the record set by fellow countryman Bernard Barmasai 10 days ago.
"The pace was too fast for the first two kilometres," Kiptanui said. "I am a little bit disappointed, but I was a little bit too tired."
Komen, who won the world 5,000m world title and then broke the distance's record on 22 August, also looked weary as he finished in 3:47.85.