Paul Dunne signed for a brilliant 65 to set the clubhouse target at 13 under after a morning of low scoring on day two of the Open de España.
With the relatively short layout at Centro Nacional de Golf softened by recent wet weather in Madrid, low scores were always a possibility with preferred lies and so it proved.
Irishman Dunne led the way as he followed his opening 66 with a seven under par effort to lead by three ahead of local favourite Nacho Elvira, Australian Brett Rumford and England's Callum Shinkwin.
England's Robert Rock and Swede Henric Sturehed were then at nine under, a shot clear of German Maximilian Kieffer, Spaniard Pablo Larrazábal and Dane Jeff Winther.
Winther got off to a flying start, birdieing the first and then picking up four shots in three holes from the third including an eagle on the fifth. When he birdied the seventh, he was six under for the day but that was still only good enough for a share of the lead.
Dunne followed up his closing eagle from Thursday with birdies on the tenth, 12th and 15th and when the British Masters supported by Sky Sports champion added another gain on the 17th, the lead was his alone again.
Winther joined him with a gain on the 11th but Dunne birdied the first after a lovely chip to get to 11 under, with Winther making three bogeys in a row from the 12th to slip back.
That left Dunne with a two-shot lead and Shinkwin as the nearest challenger after he made birdies on the tenth, 13th, 15th and 18th to turn in 32.
Dunne bogeyed the second to see his lead cut to one and a lengthy eagle putt on the fifth saw Elvira just one back after he had birdied the 13th, 15th and 17th.
The Spaniard made another gain on the sixth to share the lead but Dunne pulled away again, taking advantage of the par five fifth and then holing from 12 feet on the next after recovering from a poor tee-shot to lead by two.
Rock then joined Shinkwin at nine under and set the clubhouse target after a 65..
The two-time European Tour winner had bogeyed the third but made gains on the fifth, sixth, eighth, ninth, 13th, 15th, 16th and last.
Dunne still had three holes to play but he was relentless, holing a 15-foot right-to-lefter on the seventh to get to 13 under and stretch his advantage to three.
Shinkwin made four consecutive pars to start the front nine but got on the fifth green in two and took two putts for a birdie and a share of second alongside Elvira, who parred his last three to sign for a 66.
A Dunne three-putt from 18 feet on the 17th then cut the lead to two but he bounced back with a 20-footer on the ninth and was back in control.
Rumford joined the group at ten under after a 66 with birdies on the 13th, 15th, 17th, 18th, fifth and sixth, and a bogey on the second.
Shinkwin parred his way home to sign for a 67, a score matched by Sturehed who was level for the day after 12 holes but finished fast with an eagle on the 13th and birdies on the 15th and 17th.
Winther recovered from his stumble with a birdie on the last in a 67, a score matched by Kieffer.
Larrazábal often brings fireworks and after starting the day in a tie for 63rd, he made nine birdies and two bogeys to move into the top ten.
Australian Marcus Fraser, American Sihwan Kim and Frenchman Mike Lorenzo-Vera were then at seven under, a shot clear of a group including Andy Sullivan.
The Englishman started with a 75 on Thursday but went 12 shots better on day two, firing his second 63 of the season to get to six under.
Sullivan birdied the 11th, 15th, 17th and 18th, with an eagle on the 13th to turn in 30. When he birdied the first and eagled the fifth, Wayne Riley's tournament low of 61 from 1988 was in sight before the 30 year old parred his way home.
Marcel Schneider also signed for a 63 to sit a at five under. The German made a hat-trick of birdies from the 11th and four in a row from the 15th to turn in 29 and then bounced back from a bogey on the fourth with an eagle on the fifth and birdie on the eighth.