England's Matt Wallace and Australia's Marcus Fraser are joint leaders on 13-under going into the weekend of the Italian Open, but Pádraig Harrington and Shane Lowry both missed the cut on a day of frustration.
Wallace had a six-way share of the lead after the first round and solidified his place at the top with a 65 at Golf Club Milano on Friday.
But Fraser was the star of the day, shooting a career-best 62 to earn his place at the summit with a blemish-free card of nine under par.
Wales' Jamie Donaldson and Thailand's Kiradech Aphibarnrat lie two shots off the leading pair after hitting matching 67s, both men capping their card with eagle threes, at the ninth and 14 respectively.
Defending champion and home favourite Francesco Molinari was also circling the business end of the leaderboard, sitting three strokes back on 10 under.
Paul Dunne, meanwhile, is back on six under par. The Greystones man show a two-under 69, which included an eagle on the par-five 14th. Graeme McDowell is two back after carding a bogey-free 69.
Lowry's 71 left him two-under for the tournament and outside the cut mark, while Harrington also shot 69 but headed home early on level par overall.
Fraser, who put together a streak of five successive birdies between holes eight and 12, told EuropeanTour.com: "I felt like I've putted well and scrambled well this week. Today I took it to a new level with the putter.
"I felt like I putted well yesterday and I probably out-did it today. I'm pretty proud of myself and it's quite reassuring that I still can play golf!"
Ryder Cup captain Thomas Bjorn was among those set to miss the projected cut of two under, a fate shared by the elder Molinari brother, Edoardo, Martin Kaymer, Oliver Fisher, Padraig Harrington and Danny Willett.