Erlandsson shot a 4-under 68 in his second round to reach 9-under-par 135, good enough for a one-shot lead over four players at Golfclub Munchen Nord-Eichenried.
'I did start out a little bit intense today, but I managed to get an early birdie and from there on I tried to relax and I'll try to do that tomorrow as well,' said Erlandsson, 32, who is still seeking his first win on the European Tour.
Though he has never held a weekend lead on the European Tour, Erlandsson thinks he knows what the key will be his first time around.
'It is an old cliche, but I am trying just to concentrate on one shot at a time and not get too far ahead of myself,' he said.
Friday, his round included just one bogey at the 10th, where his approach shot missed the green left. He buffered that mistake with five birdies -- four of them coming on putts outside of 12 feet.
His hot putter kept Erlandsson ahead of a talented group of players who are tied for second place.
Among them, defending champion David Howell, who shared the first-round lead with Erlandsson and two others, shot a 3-under 69 to get to 8-under 136.
Howell -- a lock for the European Ryder Cup team and the Order of Merit leader for the entire season -- was joined at minus-8 by Alejandro Canizares (65), Mattias Eliasson (66) and Soren Hansen (66).
Not only is Howell looking to become the first ever wire-to-wire Order of Merit champion, he is also in a race to win his second BMW title this season after claiming the BMW Championship in May.
Howell's ticket to the K Club is assured, as are the tickets of several other players who are nonetheless challenging this week.
Among a group of six players who are tied for sixth place are Paul Casey (67) and Luke Donald (69), also locks for the European team. Joining them at 7 under were Marc Cayeux (66), Robert-Jan Derksen (68), co-first-round leader Garry Houston (70) and Damien McGrane (68).
There are also golfers who are trying to play their way onto the team this weekend, and others who may have had their chances dashed by missing the 1-under cut line.
Thomas Bjorn, who needs a victory this weekend, shot a 69 on Friday to move into a tie for 29th place at 4 under. Johan Edfors, in need of at least a second-place finish, is one shot further back following a 69.
Paul McGinley, who currently occupies the 10th Ryder Cup spot and final automatic berth, missed the cut at 3 over.
Paul Broadhurst, currently 11th on the points list, has some ground to make up. He made the cut on the number after a 71.
While he failed to make the cut at 6 over, European Ryder Cup captain Ian Woosnam will certainly be around for the weekend.
Woosnam is set to announce his captain's picks following the final round on Sunday.