At 6-under-par, McGinley leads by a stroke over Michael Jonzon, Neil Cheetham and Craig Hainline of the United States. David Park and Sam Walker are two shots back, while three others shot 69 and trail by three.
McGinleys day got off to a sweeping start, when, after a booming drive on the 483-yard par-5 10th (his first hole of the day), the 34-year-old stuck a wonderful second shot to eagle range.
I needed a 5-wood to make the green on my first hole for the eagle, he said, because there was still a lot of dew around, but I hit it to 20 feet and made the putt.
I cant remember ever starting my round with an eagle before.
McGinley would go on to record five more birdies against just a single bogey on his day.
Basically it was a good round of golf. I hit a lot of greens and a lot of fairways. Gave myself a lot of opportunities. Its a great score round this course.
At a length of 7,259 yards, the Red Course at Dar-es-Salem is a formidable track, upon which anything much below 70 is a good number.
Another with one of those solid scores was Cheetham, who at 33 years of age recorded his best finish on the European Tour earlier this year with a tie for eighth at the Sao Paulo Brazil Open.
Thursday, the Englishman shot a fine round of 68.
I putted fantastic, Cheetham said. Drove the ball okay, indifferently really. Hit some lovely shots and some poor shots but my short game was great as it has been all year.
Eighth in Brazil was my best ever finish and gave me confidence. Then I missed the cut the week after. That probably did me good as it brought me back down to earth with a jolt. But I put in a bit of hard work last week.
Full-Field Scores from The Moroccan Open