South African Hendrik Buhrmann carded a 6-under-par 66. He shares third place with countryman Hennie Otto and Englishman Steve Webster.
Rumford got his round going on the 10th hole at Erinvale Golf & Country Club. He opened quickly birdieing the par-4 10th and came back with a birdie at the par-5 13th. He moved to 3 under when he rolled home a birdie try on No. 15.
The Australian cooled around the turn with five straight pars, but his best play was yet to come.
'I holed putts from about ten feet at the first and about six feet at the second and although they weren't for birdie, they felt just as good because they helped me keep the momentum going, Rumford said.'
Rumford again took advantage of a par 5, this time converting a birdie at the par-5 third. He made it two straight when he came back with a birdie at the fourth. He went on to birdie the fifth and sixth to make it four consecutive birdies, which moved him to 7 under.
He still had some magic left though. He dropped a 9-iron inside 15 feet at the par-4 ninth to set up his final birdie try of the day, which gave him a share of the course record of 64.
'Leading from start to finish is probably the hardest way to win a golf tournament but I proved to myself in St. Omer that I could do it,' said Rumford, who was in the first group off the back nine in the morning group Thursday. 'It gives you confidence and confirms that you are able to compete at this level.'
Rumford was referring to his first European Tour victory which came last year at the Aa St. Omer Open.
Dodd, who also began on the back nine Thursday, matched Rumford's birdie on the opening hole. He birdied three of the last five holes on his first nine, to head to the front at minus-4.
The Welshman drained a birdie try at the par-3 second to start a run of three straight birdies. However, Dodd bogeyed the par-5 sixth before his birdie at the ninth gave him solo second.
'I do like it here, I like the course and I think that was reflected in the way I scored today,' said Dodd. 'With the weather the way it is at home over the winter, you are not really able to do any quality practice so you don't really know how you are going to play when you come out. It wasn't totally unexpected, but it was nice at the same time.'
New Zealand's Stephen Scahill notched a 5-under-par 67 to join Nico Van Rensburg in a tie for sixth place. Miguel Angel Jimenez heads a group of seven players at 4-under-par 68. Standing alongside Jimenez are Alastair Forsyth, Tyrol Auret, Raphael Jacquelin, Alan Michell, Colin Montgomerie and Marcel Siem.
Trevor Immelman opened his title defense with a 1-under-par 71. That was good enough for a share of 34th.