Englishmen Simon Dyson and Oliver Whiteley lead a group of players tied for second place at 5-under-par 66. They stand alongside Sven Struver and Jorge Benedetti at Fontana Golf Club.
Brier, who won this event twice when it was part of the Challenge Tour, opened with birdies on one and three. However, he gave those strokes back with bogeys at the sixth and eighth.
The 38-year-old fought back with a birdie on the par-5 ninth. Brier then holed his 7-iron tee shot at the par-3 11th to jump to minus-3.
'I saw the hole-in-one all the way,' Brier said. 'There was a little drizzle, but it was a perfect shot. The wind was just off the left and I just drew it in and it bounced three feet from the hole and rolled in.'
He drained a birdie effort at the next to fight back within one of the lead.
Brier was not done climbing the leaderboard. He poured in a birdie try on the par-4 16th, then closed with a birdie on the par-5 18th to take the overnight lead.
'The birdie on the last just put the icing on the cake of a perfect day,' stated Brier. 'I was comfortable with the putter all day. At the start of the day, I was hitting it really close and got a couple of birdies and then I struggled a bit. After the ninth, I hit all the fairways and greens and had lots of chances.'
The Austrian leads after one round for the fourth time in his European Tour career. However, Brier has finished no better than 25th in those previous three events.
Dyson played the front nine in 3 under with four birdies and a bogey. His back nine included seven pars and back-to-back birdies from the 15th.
Whitely started his round on the 10th tee and stumbled to a bogey on his opening hole. After three straight pars, he dropped in consecutive birdies from the 14th.
The Englishman made the turn at 3 under thanks to a birdie on 17. Around the turn, Whiteley birdied the first, then sank birdies on four and five to grab a share of second place.
Struver got off to a hot start with three birdies over his opening five holes. He also birdied the ninth to make the turn at minus-4. The German stumbled to a bogey on the par-4 12th. He recovered that stroke with a birdie at 15, then birdied the 17th to tie for second place.
Benedetti tripped to a bogey at the second, but he quickly erased that error. The 34-year-old ran off four straight birdies from the third. He also birdied No. 9 to make the turn at 4 under. Benedetti birdied 13 and 14 to get to 6 under, but cost himself a share of the lead with a bogey at the last.
'Today was my first round on the European Tour,' said Benedetti. 'So the only thing going through my head was to have fun and that's what I did. I had a great day today.'
Eight-time Order of Merit champion Colin Montgomerie posted a 4-under-par 67. He was joined in sixth place by Spaniard Miguel Angel Jimenez, Benn Barham, Gregory Bourdy, Alastair Forsyth, Ian Garbutt and David Higgins.
Soren Hansen had a chance to be the first-round leader, but he struggled down the stretch. Hansen started on the back nine and birdied seven of his first 11 holes. However, double-bogeys on Nos. 4 and 5 dropped him to minus-3 and into a share of 13th with six other golfers.