Sam Brazel made six birdies in ten holes to surge up the leaderboard early on day two of the Hero Indian Open at DLF Golf and Country Club.
Overnight leader Stephen Gallacher was due out in the afternoon and he remained at the summit at five under but Brazel got to four under after 11 holes to join the nearest challengers.
Gallacher's fellow first round leader Julian Suri was also at four under after making a single bogey on the front nine, alongside Scot Richie Ramsay, England's Callum Shinkwin and later starters Christiaan Bezuidenhout, Robert Karlsson and Pablo Larrazábal.
American Suri started his round with six pars and that was enough to keep him in a share of the lead but a bogey on the 16th meant that Gallacher was alone at the top without hitting a shot.
Jack Singh Brar had made an impressive move on the front nine with birdies on the fourth, fifth, seventh and eighth but a bogey on the tenth dropped the Englishman back to three under.
After an opening 72, Shinkwin was making progress with gains on the second and third and two more on the eighth and ninth had him within one at the turn.
Ramsay also moved into the group in second as he recovered from a bogey on the second with birdies on the fourth and seventh.
That did not match the recovery of Australian Brazel, however, who after a bogey on the first made a hat-trick of gains from the second and further birdies on the eighth, tenth and 11th.
American Berry Henson, Thai Poom Saksansin and Austrian Bernd Wiesberger were all out on course at three under.
