England's Richard Bland (67) led by one at the halfway stage in Turin after moving to 12-under par 132. Behind him were the Scot, who birdied seven of his last 11 holes, France's Gregory Bourdy (64), Spain's Gonzalo Fernandez-Castano (65) and South African Garth Mulroy (67).
Warren reached 10 under par after two days at last year's Alfred Dunhill Links Championship, en route to finishing fifth. Before that, one of Warren's best first 36-hole score was eight under on his way to his maiden Tour success at the 2006 Scandinavian Masters.
The 31-year-old said: "I am confident in what I am doing at the moment and patience is also a factor. I'm really pleased as coming down those last 11 or 12 holes I didn't have a putt outside of 15ft. I wasn't trying to get to 11 or 12 under, I was just trying to get as low as I could, and it felt really good."
In contrast, Warren's fellow Glaswegian Scott Jamieson bogeyed the last two holes after reaching nine under par after 14. He signed for a 69 for a share of 22nd place on seven under par. "I didn't play well at all and I'm very disappointed to get so close to the lead and then throw it away near the end," Jamieson said.
"To throw two shots away there at the finish, and to also bogey 18 for a second day running, is annoying."
Alastair Forsyth sneaked through to the weekend to boost hopes of moving from his current 124th Race to Dubai standing and to inside the top 115. Forsyth carded 71 to move to five under par and a shot inside the cut-off mark.
"I've got through to the weekend but it could have been so much better," he said. "I didn't play brilliantly but I missed so many putts it's just mind-boggling."
The Fife pair of Peter Whiteford (72) and George Murray (70), along with David Drysdale (72), missed the cut by a shot. Murray won a Jeroboam of Italian bubbly for his second Tour ace when he holed out at the par-three third hole – less than an hour before Spain's Jorge Campillo was presented with the keys to a £90,000 BMW 6 Series for an ace at the 15th.
"I got a hole in one at Wales last year and it was the wrong hole, as well," Murray joked. "But while it's nice to be presented with a prize, I'm playing rubbish and I've had enough. I should be playing much better than I am but I just can't hit my irons. That used to be the best part of my game and it's just rubbish.
"The only good shot I hit all day was a 5-iron at three, as I hit a wee fade and it took just one bounce and rolled in. But then there were only about two folk there to see it.
"It's just a shame it wasn't the car as it's worth £90,000. It is sitting on the 15th tee and I actually sat against it but that's the closest I got."
Stirling's Craig Lee (72) also missed the cut on two under. Helensburgh's Gary Orr pulled out of the event with a back injury without even teeing off yesterday.