Laurie Canter began his 2020 Portugal Masters campaign with a spotless 64 to set the early clubhouse target at Dom Pedro Victoria Golf Course.
The Englishman, who is searching for his first European Tour title, fired seven birdies - including three in a row from the fourth - and no bogeys to get to seven under par in favourable playing conditions in Vilamoura.
That left him a single shot clear of fellow early starter Jonathan Caldwell, who carded seven birdies and a single bogey in his 65, and Scotland's Liam Johnston who was six under after 12 holes.
George Coetzee, Matthew Jordan and Sebastian Soderberg were in the clubhouse on five under.
Canter started brightly on Thursday morning, following up a birdie on the second with a hat-trick of gains at the fourth, fifth and sixth to jump to four under.
The 30-year-old then took advantage of the par three eighth to reach the turn in 30 shots.
He continued to create chances as he began the back nine, narrowly missing birdie putts from just inside ten feet at the tenth and 11th.
Canter got a huge slice of luck at the 12th as his approach shot narrowly avoided the water and he went on to save par and remain at five under.
Another birdie chance came and went at the short 13th as his 20 foot effort just evaded the hole, while he also missed his birdie try from a similar distance on the 14th.
Canter finally broke his run of pars with a birdie from five feet on the 15th before just missing another birdie putt from around 15 feet at the 16th.
After his eagle putt from 20 feet at the 17th pulled up just short, Canter tapped in for a birdie to move to seven under before closing his first round with a par.
