The 20-year-old who broke into the first team last season scored twice as a strong-looking side dominated at Woodside Park in a 4-0 win.
With Ian Walker, Mauricio Taricco, Ramon Vega, Stephen Clemence and Matthew Etherington all in the starting line-up it took Chris Hughton's men just 10 minutes to break the deadlock. Dave McEwen ran at the home defence before releasing Piercy - in excellent form at the start of the season - who cut in from the right and finished well with his left foot.
McEwen was involved in the second goal as we continued to push forward. This time he exchanged passes with Yannick Kamanan and the third-year trainee from France cooly finished his one-on-one opportunity.
More chances came and went but it remained 2-0 until the 64th minute when Piercy scored his second and our third. It was a similar effort to his opener - cutting in from the right and scoring with his left foot. Mark Gower completed the scoring, slotting home after a one-two with Neale Fenn.
Boss Hughton was naturally in higher spirits than after his side's FA Premier Reserve League defeat against Coventry City. "It all went very well, ideal for us," he said. "We were always stronger and perhaps the only disappointment was that from lots of possession, and we had to work hard for that possession, we didn't score more goals. Our finishing could have been better.
"It was very positive for us. Sometimes these games are very tight and a bit of a battle but we saw plenty of the ball and that gives you the opportunity to work at things like if you're up front, receiving the ball to feet and in midfield, having more time and space to play. It was a good run out, excellent for us."
It might be a whole new ball game in the reserves' next match - away to Wimbledon in the FA Premier Reserve League on Wednesday September 6.
John Piercy was on fire again as the reserves comfortably beat Bishop's Stortford in Wednesday night's friendly.