Lundberg shot an even-par 72 at Dublins K-Club to finish the day at 12-under 204, one shot clear of Henrik Bjornstad (70) and Jarmo Sandelin (65).
When all was said-and-done for Lundberg, it appeared fine on paper, but in reality, the round wasnt as clear-cut as it seemed.
Through his first six holes on Saturday, it looked as if the young Swede might be in trouble, as he suddenly found himself 2-over for the day following a string of early bogies.
His three-shot overnight lead had completely disappeared, and now at minus-ten, he trailed Bjornstad by two, as the young Norwiegan had ripped off three consecutive birdies from the fourth through the sixth holes.
Lundberg was not to be undone, however, and he responded in nice form, birdying the seventh and the 12th to make up some ground.
In the meantime, Bjornstad went the opposite direction, with three bogies over the remainder of his round to finish with 70.
A final birdie at the finishing par-5 18th for Lundberg, and he pulled ahead of the field for good.
The way I played today, I am very satisfied being in the lead, claimed Lundberg, whose best finishes this year have been fifth-place showings at the South African and Deutsche Bank Opens.
I played quite badly and am a little surprised none of the guys behind me shot lower.
Despite Lundbergs comments, a few did go low Saturday, and the real threat in the final round may come from four-time winner on the European Tour Sandelin, whose bogey-free 65 on Saturday was the best score of the day at the K-Club.
Sandelin birdied five of his last eight holes of the day ' including the 18th ' to climb all the way from minus-four to 11-under, just one shot back.
He is looking for his first win of the year, and his first since 1999.
Far too long Ive been here, stated Sandelin of his recent sluggish form. Im now increasing my practicing a lot. Theres no short cut, especially when you dont have the talent of a Tiger Woods.
Likewise, Irelands own Padraig Harrington is searching for his first victory of the season. However, his play of late has been wonderful, having finished second on four different occasions already. His latest came just last week, at the Murphy's Irish Open.
The crowds were tremendous today, said Harrington, who birdied the 17th and eagled the 18th to end in outright fourth at 10-under. They were right behind me, even with the late birdie.
Unfortunately, not everyone concluded their rounds with such fireworks as Harrington.
Darren Clarke triple-bogied No. 17 to fall into fifth-place at minus-nine, while Costantino Rocca bogied the 14th and 17th holes to end tied with Paul Casey, Michael Campbell and Ian Woosnam at 8-under, four shots back.
Full-field scores from the Smurfit European Open