Defending champion Andy Sullivan joined Marc Warren at the top of the leaderboard after the Englishman and Richie Ramsay carded the lowest rounds of the European Tour season at the Portugal Masters on Friday.
The magnificent Sullivan surged into a share of the lead at the halfway mark with a blemish-free 10-under round of 61 of the highest order at Victoria Clube de Golfe.
Sullivan gave himself a great chance of becoming the first player to win back-to-back Portugal Masters titles, having been crowned champion when he won by a record nine shots last year.
Three-time European Tour winner Sullivan spoke of the need for his putter to warm up ahead of the tournament in Vilamoura and it was red hot as he went out in 31, before coming up with another six birdies after the turn.
Warren held a one-shot advantage after the first round and a six-under 65 enabled the Scot to head into the weekend as joint-leader.
After starting at the 10th hole, Warren held a three-shot lead at one stage but Sullivan's charge pegged him back, with his only bogey of the round coming late on - at the seventh for the second successive day.
Warren's compatriot Ramsay had earlier made his move with a stunning exhibition which included 11 birdies in favourable conditions to put himself in the hunt for a first title of the year. He is now among eight players sitting four shots off the pace.
Padraig Harrington and Jens Fahrbring, who needs a top-two finish to keep his card, are just a shot adrift of the leading duo following rounds of 64 and 63 respectively, while David Lipsky is well poised on 12 under.