England's Ross Fisher overcame an injury scare to move a step closer to his fifth European Tour title.
The 31 year old slipped walking off the first tee when he resumed the Portugal Masters and feared for a while he might have to withdraw.
But after a physio was called for and strapping applied to his left foot, Fisher battled on and thanks in large part to a 22 foot eagle putt on the long 17th added a 67 to his opening 65.
"I didn't think anything of it at first and for two or three holes it was okay, but then it started to get really sore," he said.
"The physio told me I was not doing any damage by playing on. It was uncomfortable for a while, I was feeling it again at the end and I'm just very relieved to get through.
"To be leading is very, very pleasing. It was really difficult to get through the ball and it made it quite challenging to pick the right club.
"My balance was not very good, but I tried to grind it out and fortunately I came through with a decent score."
On ten under par at halfway Fisher leads by three from Scot Stephen Gallacher and Austrian Bernd Wiesberger.
Gallacher, yet to have a bogey, is seeking only his second victory in nearly 400 European Tour events, but Wiesberger has already had two this season.
Fisher last tasted success at the Irish Open two years ago, a victory which helped to secure him a Ryder Cup debut at The Celtic Manor Resort.
Since partnering Padraig Harrington to two wins against the Americans, however, he has managed only one top five finish and finds himself down at 140th in the Official World Golf Ranking.
Earlier it had looked like being Padraig Harrington's morning at Oceânico Victoria when he went two clear with six birdies in his first 11 holes.
But in a real mixed bag of a finish the 41 year old Irish star, without a European Tour victory for over four years, had a double bogey, two more birdies and two bogeys, both of those coming when he three-putted.
“I didn't really push on,” admitted the three-time Major Champion. “I made a few mistakes.
“It was all going very nicely and I made a couple more birdies after the double bogey, but I’m a bit upset about the two three-putts at the end.
“That was a pity because eight under would have been a nice return, six under for the round, eight under for the tournament, and I can forget about the double bogey. But as I say the two 3 putts are the ones that hurt a lot more.”
Wiesberger had five birdies and an eagle two at the 315 yard 15th, his sixth.
The Vienna golfer's lone dropped shot came at the difficult seventh, where his drive picked up mud and his approach finished in the greenside bunker.
“I'm feeling good,” said Wiesberger. “I didn't hit as many fairways as I would have liked to, but the rough is not up much, so the closer you get to the green, the more shorter clubs you can hit.
“It's not playing particularly long today, so a lot of wedges in and more chances to make more birdies.”
Gallacher has gone two days without a bogey as he seeks only his second title in almost 400 European Tour events - but there was only one birdie in his second round 70.
“I hit greens in regulation, so I had pretty much 35 putts,” said the 37 year old. “Some were close, some were good two putts from distance; so it was about even really.”
Of Europe’s three Ryder Cup heroes present only Francesco Molinari will be around for the weekend action.
The Italian shot a second straight 71 to make the cut on level par, but Martin Kaymer’s 75 saw him miss out on two over and Captain José María Olazábal shot a 75 for eight over.
