But he safely parred the long ninth to sign for a 66.
Pearce said: "I holed a really nice putt on the first hole for birdie, which got the momentum in the right direction.
"I managed to birdie 11 as well. I made a couple of good up-and-downs through the back nine to save par a couple of times and then I birdied the 17th and had a bit of a run through the front nine - the first four holes.
"There was a lot of good golf. I didn't quite finish it off how I'd like to but I'm pretty happy.
"The putter was pretty hot today so I rolled in a few putts from all over the place, which was nice."
Campbell reached the turn in 35 after making one birdie on the front nine but his round came to life after the turn.
He picked up three shots in a row from the tenth to get to four under before parring the next three holes.
Campbell dropped his first shot of the day at the 16th but made amends at the next, firing an eagle to get within one shot of the lead.
He said: "It was a solid round.
"I thought anything under par today would be a great score. It wasn't easy out there, that's for sure.
"So I'm really happy to get off to that kind of start. I think at most tournaments you'd take a five under first round anyway."
Australian Peter Cooke made the 27th hole-in-one of the European Tour season when he aced the par three 15th.
"I’ve played this event for a few years, I knew the flag, knew the shot and knew the club so it was pretty comfortable," he said.
"We sort of had to squint a bit and figured it must have spun back into the hole. That’s when we started jumping around."