Henrik Nystrom, who is ranked outside the world's top 1,000, was the early leader during the first round of the Estoril Open de Portugal.
The 41-year-old Swede recorded five birdies against one bogey on his opening nine before adding two birdies in three holes to sit atop the leaderboard on six under with six holes to play at the Penha Longa Golf Club at Sintra, near Lisbon.
England's Richard Bland was one shot behind after six birdies in his opening 15 holes, while Norwegian Eirik Tage Johansen and Christian Nilsson of Sweden were in joint third, a further shot behind. Seven players were on three under midway through their opening rounds.
Nystrom, who missed the cut at four of his last five European Tour events, including last week's Wales Open at Celtic Manor, enjoyed a tremendous start and was three under through three holes. His run of three birdies on the opening three par-fours was ended with a bogey five on the 434-yard fourth. But he responded by picking up birdies at holes six and eight to reach the turn in four under 32. Further birdies on holes 10 and 12 saw Nystrom well positioned to at least continue in the event into the weekend.
Bland, from Southampton, was also in a good position early on. The 37-year-old, who retained his European Tour card last year after three top-10 finishes, reached the turn in 33 after birdies at holes one, three, six and nine and a bogey at the fifth. He picked up two further birdies at holes 10 and 12 to lie one shot behind Nystrom.
The chasing pack included Thomas Bjorn of Denmark, Bristol's Chris Wood – the highest-ranked player in the field at world number 81 – former Ryder Cup ace Peter Baker and Alastair Forsyth.
England's Simon Khan has been called into the field for next week's United States Open. Khan's victory in the European Tour's flagship BMW PGA Championship at Wentworth three weeks ago did not earn him a place at Pebble Beach and he lost in a qualifying play-off at Walton Heath.
But the Essex golfer comes in as first reserve because Justin Rose, who lifted the Memorial Tournament in Ohio on Sunday, needed to have won at least one other PGA Tour event in the past year to be given an exemption.
Khan shot 67-70 in the qualifier and was part of a six-man play-off for the final five spots, but missed out when he parred and, amazingly, the other five all sank birdie putts. His call-up completes a remarkable turn of fortune for the man who was 471st in the world before Wentworth.