Manassero, coming off a win at last week's BMW PGA Championship, and Pablo Larrazabal each shot 6-under-par 66 and lead the tournament by one stroke. Larrazabal had five birdies in an eight-hole span and closed with a birdie for his 66.
Fredrik Andersson Hed, Jamie Donaldson, Chris Lloyd, Alexander Noren and Simon Wakefield all turned in 67s and are one behind the leaders. Donaldson and Wakefield were both bogey-free while the others had one bogey Thursday.
Five more players are tied at 4-under and 10 more shot 3-under 68.
Manassero, starting on the second nine of the Bro Hof Slott Golf Club, opened with birdies in his first six holes. He dropped back with a bogey at 17 but birdied No. 1. He also had a bogey at the fifth hole and got back to 6-under with a 1-foot birdie putt at 6.
Larrazabal, also starting at No. 10, had three birdies over Nos. 12-15 and went back-to-back at 18 and 1. Another birdie at the fifth hole got him to 6-under. A bogey at 7 and a closing birdie left him tied for the lead.