The duo owns a one-shot edge over Ernie Els, the winner of the last week's Genuity Championship on the PGA Tour, Charlie Wi, Olle Karlsson, Ryder Cupper Niclas Fasth and his captain at the Belfry, Sam Torrance, who made his 2002 season debut after knee surgery.
The co-leaders are also making returns to the tour in some respects. For Bjorn, this is his first competitive action of the year after a shoulder injury caused him to miss several months.
'I didnt have any expectations,' said Bjorn, who bested Tiger Woods by two shots last year. 'I knew I was swinging the club well but I would have taken anything under par for my first competitive round of the year. I knew if I went out and hit the shots Ive been hitting on the range then I could shoot 64 but it could also have all gone up in the air.'
Karlsson's absence was for a more joyous occasion. Prior to Christmas, he welcomed his first daughter, Thea, into the world and he took time off to be a father after three tournaments early in the 2002 campaign.
'Thea, my baby daughter, was born on the 19th of December and I was getting used to being a father when I went to Australia,' said Karlsson, a four-time winner on the European Tour. 'Perhaps I should have practiced instead of playing. However Ive got over the shock of being a dad and Ive practiced hard during my break.'
Bjorn opened with three birdies in his first six holes at the Majlis Course at Emirates Golf Club before adding another birdie at No. 11. The Dane matched Karlsson for the lead with a birdie at the 17th hole to reach minus-five.
Karlsson took a different approach to his 67, mixing five birdies, two bogeys and an eagle. His birdie at the ninth, his final hole of Thursday's opening round, gave him the clubhouse lead over his playing partner, Els.
Els, a two-time U.S. Open champion, collected five birdies and a bogey while showing no hangover from his win on the PGA Tour last weekend.
'I felt good today,' said Els, who won the Heineken Classic in early February. 'The celebrations and all that stuff was done and dusted. I like the course and Im ready to play.'
Torrance, the European Ryder Cup captain, came out on fire with four birdies in a row, starting at the second hole. He picked up two birdies and two bogeys the rest of the way for his 68.
'It was just down to wear and tear,' said Torrance of his knee injury. 'I hadnt had any problems before and it seems fine now. Today was all a bit of a shock, to be honest, but a nice way to start the year.'
Pierre Fulke, also a member of the European Ryder Cup team, posted a 3-under 69 and shares eighth with Mark Mouland, Paul Broadhurst, Gregory Havret, Sven Struver and John Bickerton.
Padraig Harrington shot a 2-under 70 while Colin Montgomerie carded a 1-under 71 Thursday and is part of a logjam tied for 28th.
Darren Clarke, Justin Rose and Nick Faldo are part of a group at even-par 72, five shots out of the lead.
Full field scores from the Dubai Desert Classic