England's Andy Sullivan shot a magnificent 10-under-par 61 in his second round to earn a share of the lead at the Portugal Masters.
The 30-year-old Ryder Cup player carded four birdies in his opening six holes to reach the turn in 31 and then added another six birdies during a brilliant back nine to move on to 14 under for the tournament.
That left the defending champion level with overnight pacesetter Marc Warren of Scotland (65) at the top of the leaderboard, with Ireland's three-time major winner Padraig Harrington (63) and Sweden's Jens Fahrbring (64) a further shot back.
Sullivan, who could move into the top 50 of the world rankings with a strong showing at Victoria Clube de Golfe, was not the only player to record a 61 on Friday.
Scot Rich Ramsey had earlier achieved that feat in a round that included 11 birdies and a single bogey on the 16th, leaving him four shots adrift of the leaders.
The two 10-under scores equal the lowest round of the season on the European Tour, matching Tyrrell Hatton's 62 at St Andrews at the Alfred Dunhill Links Championship.
Ramsey told www.europeantour.com: "It sort of just came out of nowhere. I've been in sort of a downturn but that one's for my daughter.
"She's been out supporting me, my smallest supporter but my biggest supporter at the same time. She needs something to shout about because dad hasn't been playing so good."
Warren and Sullivan do not have much breathing space at the top of the leaderboard heading into the weekend, with 15 players within four shots of them and a further nine in the chasing pack on nine under.
Ireland's Harrington is aiming to win on the European Tour for the first time since 2008 - the year he claimed two of his three majors.
Fahrbring, meanwhile, needs a top-two finish in order to secure his European Tour card for next season.
America's David Lipsky sits a further shot behind alone in fifth with Finland's Mikko Korhonen, Englishman Paul Waring and French pair Raphael Jacquelin and Edouard Espana all on 11 under.
However, it was a terrible day for Englishman Eddie Pepperell who started the day in joint-second but is now struggling to keep his card after shooting a five-over-par 76 to miss the cut by two strokes.