The Irishman, famous for holing the winning putt for Europe at The Belfry in 2002, carded two birdies and an eagle to reach four under after eight holes as he continues to recover from knee surgery.
That gave him a share of a four-way lead, alongside England's Richard Finch, France's Julien Guerrier and Swede Niclas Fasth - a teammate of McGinley's in 2002.
Hull golfer Finch had his fourth birdie on the long 16th and, after missing the green on the 198 yard 17th and making a bogey, he came straight back with a six foot birdie on the next to complete a back nine of 32.
McGinley joined him on four under with an eagle at the 562 yard 16th.
On a congested leaderboard seven players were tied for fifth on three under during the early exchanges.
Welshman Jamie Donaldson, his compatriot and Trophee Hassan II winner Rhys Davies, Scot David Drysdale, big-hitting Spaniard Alvaro Quiros, Italian Omega Mission Hills World Cup winner Francesco Molinari and South African Thomas Aitken all made promising starts in pursuit of the €250,000 first prize.
Sergio Garcia, Luke Donald and Martin Kaymer were among the later starters.