The second round was suspended for the day due to fog. The round will resume at 3:30 a.m. (ET) Saturday with the cut to be made after the round is complete. The third round will commence after that.
David Higgins completed a round of 6-under 66 to move into second place at 9-under-par 135. Matthew Morris was also at minus-9 through seven holes of his second round. John Bickerton is one stroke behind that duo at minus-8, but has only completed 11 holes of round two.
Sullivan, a member of the Challenge Tour, opened his round with a birdie on the par-5 third to move to 9 under. He later picked up his second birdie in two days at the par-3 eighth.
Around the turn at Santo da Serra Golf Club, Sullivan climbed back into the lead by himself at minus-11 with a birdie on the par-4 13th. The 28-year-old faltered to a bogey at the par-4 18th to head into the clubhouse at minus-10.
'It wasn't until we were really on the 11th that I realized that Dave tied me and I thought I better start making some birdies,' said Sullivan, who was paired with Higgins. 'It's not a case of trying harder, but you are conscious of it when your playing partner is going so well. Dave played fantastic and it does keep you going. I'm just happy that I'm still in the hunt.'
Higgins caught fire right out of the gates on the front nine. Higgins rolled in three consecutive birdie tries from the second to get to 6 under.
After a pair of pars, the 32-year-old Higgins birdied his next four holes to move to 10 under par and a share of the lead. The Irishman parred seven consecutive holes before he tripped to a bogey at 18.
'I holed a few nice putts on the front nine and then didn't get anything on the back nine, but I'm playing nice so it's ok,' said Higgins. 'It was just the 18th where I came off my drive and hit a bad one because the rough down the right side is tough and I knew as soon as I hit it that it was going to end up there. You've got to hit it up the left side there and as a result I made bogey.'
Morris ran off three straight birdies from the 10th to open his round. He stumbled to a bogey at the par-3 15th to slide one shot back and parred the next hole before action was halted for the night.
Stephen Scahill, who shared the first-round lead with Sullivan, only managed a 1-over 73 to slide to 7-under-par 137. He was joined there by Magnus P. Atlevi (68) and Rolf Muntz (67).
Andrew McLardy moved into a tie for eighth place with a 1-under 71 and stands at minus-6 through two rounds. He was tied there by Garry Houston, Robert-Jan Derksen, Alvaro Salto, Gary Orr, Shaun P. Webster, Benn Barham, Nicolas Colsaerts and Gregory Bourdy, all of whom have not completed their second rounds.