Paul Dwyer lost a playoff last year to Joakim Backstrom, but is back in the hunt this season. He carded a 5-under 66 and is tied for second place with Jean Hugo (69) and Cesar Monasterio (68) at 6-under-par 136.
Klas Eriksson (71), Martin Maritz (67) and Nicolas Vanhootegem (69) are knotted in fifth place at minus-4.
Nystrom began his second round on the back nine and wasted little time in breaking into red numbers. He birdied the 10th, then added another at the 12th, a hole he has birdied in each of the first two rounds.
The Swede birdied 15 and 18 to make the turn at an impressive 4-under-par 31.
Nystrom did not get off to a great start on his second nine Friday. He bogeyed the 10th, then parred his next six holes before a spectacular finish that gave him the 36-hole lead.
He birdied the eighth to reach 6 under par, then eagled the par-5 ninth, a hole Nystrom bogeyed on Thursday. The finish gave him the second-round lead for the second time on the European Tour and the Swede is hoping for a better finish than last time.
At the 2004 BMW Russian Open, Nystrom finished 73-70 to take fifth place. He will be in search of his first victory on the European Tour and that's something Nystrom desperately wants.
'I want to win this season,' said Nystrom. 'I have been playing well since the beginning of the year, but haven't had that many starts. So, when I have played, I have missed a few cuts by just one or two shots, but I am pushing forward and trying to do well when I get the chance to play. Wales was the first one that I managed to do that.'
At the Wales Open at the beginning of the month, Nystrom tied for seventh place. He has made only three cuts in nine starts this season on the European Tour, but is happy with his progress.
'I made a good climb on the Order of Merit in Wales,' said Nystrom. 'When you get higher on the list it is a lot easier to see that you are going to make the top 115. When you are way back you start to count tournaments and it never works out, so it is nice to have made a good move up the Order of Merit.'
Dwyer did not get off to a good start on Friday as he was 3 over par through his first six holes. He birdied four in a row around the turn, then birdied four of his last five to get within two.
'I think if you have had a result somewhere before and you go back there you just feel more relaxed about the week. That's how I feel this week -- I just hope to go one better this year,' said Dwyer. 'I was disappointed not to win the playoff last season, but you have got to look at the big picture and this time last year finishing second here was a massive result for me and played a big part in me getting my tour card through the Challenge Tour Rankings.'
Hugo mixed five birdies and three bogeys for his 69, while Monasterio tallied four birdies and one bogey for his 68.
First-round leader Felipe Aguilar struggled to a 2-over 73 on Friday and is tied for eighth place with Jesus Maria Arruti (69), Jorge Berendetti (68), David Dixon (71), Chris Gane (70), Adrien Mork (71), Juan Parron (71), Lee Slattery (70) and Shaun P. Webster (68) at 3-under-par 139.
Backstrom made the 36-hole cut on the number Friday. He only managed an even-par 71 and played two rounds at 3-over-par 145.