Ilonen leads by 2 at Nordea Masters
The 33-year-old Finn shot a 7-under 65 in wet conditions on Saturday to move to an overall 18-under 198 on the Bro Hof Slott course.
Noren posted 8-under 64 for an overall 200.
The 114th-ranked Ilonen, whose last Tour victory was winning this event in 2007, capped his round with back-to-back birdies at Nos. 13 and 14. He then eagled the par five 15th where his short wedge shot into the green spun back into the hole.
''It was a great run of three holes,'' Ilonen said. ''I need to shoot another low score and I know I can do it.''
Ilonen finished second this year in both the Hassan II Trophy in Morocco and the China Open.
The 30-year-old Noren is also hoping to end his winless drought since victory at the Nordea Masters two years ago.
Sweden's Jonas Blixt (66) and Italy's Matteo Manassero (71) share third place on 14 under.
BMW PGA Championship winner Manassero, who led here for the opening two days, birdied three holes in succession from the 13th hole to move to 16-under but then double-bogeyed the final hole.
Sweden's Peter Hanson, the highest ranked player in the field at No. 23, struggled with a 73 to slip back into a share of 36th place at 5-under.