Ryder Cup Dane Björn played some tremendous golf as he recorded eight birdies to race to 13 under with a hole to play.
But the World Number 193 - who was in contention for last week's Celtic Manor Wales Open before a disappointing final round - bogeyed the par five last after finding trouble from the tee to join Del Moral on 12 under at halfway.
After driving right into the trees, Björn could only find rough with his second and his third flew the green.
He had an eight foot putt for an up-and-down par but when that slid by the Spaniard was left with a well-deserved share of the lead.
“I hit every fairway until the last hole, and I only missed one green,” said Björn.
“It was really steady and my golf felt easy for once, which made a nice change.
“It was a shame about the last, but I’ve still got to be happy about a 65. You normally have at least one bad hole in a round of golf, it’s just a shame it had to be the last. But I like the course – I seem to find a nice rhythm round here.”
The 24 year old Del Moral completed a brilliant back nine 31 at Penha Longa Golf Club and put his superb display down to an improved fitness regime.
"I've started working a lot more on my fitness levels away from the course. I've started training hard, because that's what all the top players do," said Del Moral - seeking a maiden European Tour win.
"I feel much better out on the course now. It's had an effect much sooner than I'd thought, but I'm very happy. Hopefully it can continue having the same effect for the next two days and the rest of the season.
"I'm going to go for a run on the beach this afternoon, and hopefully I'll lose a few more pounds and go even lower tomorrow!"
The Spaniard was in doubt as to which part of his game sparked that stunning run on the back nine.
"I've played beautifully these last two days, and putted very well. I made a lot of clutch putts, particularly on the back nine," he added.
"So my putting definitely made the difference between a good round and a great round today."
Three players share third on ten under - Ireland's overnight leader Damien McGrane joined by the English duo of Steve Webster and Robert Rock.
Webster's last European Tour title came on Portuguese soil at the 2007 Portugal Masters and the 35 year old turned in 34 after starting at the tenth before registering a hat-trick of birdies from the first.
"I've not played brilliantly this year so far, but I've brought a new putter with me this week and I seem to have found something with my putting stroke," said Webster.
"So it was nice to make a few 20 footers for a change, instead of just hitting it close all the time. Six birdies today tells its own story."
Irishman McGrane looked on course to set the clubhouse target for the second day running as he advanced to 11 under for the week with six to play.
But the former Volvo China Open winner came unstuck at the 434 yard fourth when his wayward approach finished on the root of a tree and forced him to play away from the flag, leading to a double bogey six before a birdie at the ninth, his last, repaired some of the damage.
Coles mixed eight birdies with two bogeys in his 66 as the Challenge Tour graduate looks for a second top five finish of the season.
“Before this week, I haven’t been hitting the ball well,” admitted Coles. “I’ve been chipping poorly and putting terribly.
“So if you can’t put it close, I suppose you can’t just blame poor putting for high scores. But over the last couple of days, I’ve kept it pretty straight, and managed to create plenty of chances, a few of which I’ve taken.”