Callum Shinkwin fired a six under par 66 to set the clubhouse target on day one of the D+D REAL Czech Masters.
The Englishman arrived at Albatross Golf Resort after a five-week break but showed no signs of rust, making eight birdies to lead the way ahead of South African Dylan Frittelli and Swede Pontus Widegren.
Felipe Aguilar, Jaco Ahlers, Chris Hanson, Peter Karmis, Oscar Lengden and James Morrison were then at four under, with 16 players within three shots of the lead.
Shinkwin birdied the first but gave the shot straight back on the third before making further gains on the fourth, fifth, ninth and tenth. Another birdie on the 13th saw him lead on his own but he dropped a shot on the next after finding trouble off the tee before putting his tee-shot to five feet on the 16th to share the lead again.
A closing left-to-righter from 20 feet then gave him a round of 66 and the lead on his own.
Frittelli - the LYONESS OPEN powered by ORGANIC+ champion - started on the back nine and birdied the tenth, 11th and 14th before a double-bogey on the 16th threatened to derail his progress. The 27 year old recovered admirably, birdieing the 18th, fourth, sixth and ninth to get within a shot of the lead.
Qualifying School graduate Widegren turned in 33 with birdies on the 14th, 15th and 17th before adding gains on the first, seventh and ninth to go with a single blemish on the third.
South African Karmis birdied the tenth, 11th, 17th and second and when he put an approach to six feet on the sixth, he shared top spot. A bogey on the eighth coupled with Shinkwin's closing birdie then saw him fall back.
Countryman Ahlers turned in 35 from the tenth with three birdies and two bogeys but made progress on the front nine with gains on the first, sixth and ninth.
Swede Lengden was bogey-free in his round, making birdies on the first, third, tenth and 16th, while England's Morrison was also flawless recording gains on the second, 12th, 13th and 18th.
Chilean Aguilar was another man with a clean card as he made birdies on the 14th, second, sixth and ninth, with Englishman Hanson dropping a single shot on the 15th after birdies on the first, second, fifth, ninth and 12th.
Defending champion Paul Peterson was then at three under with four birdies and a single blemish while a hat-trick of gains from the 16th helped playing partner Jamie Donaldson to the same mark.
European Tour winners Grégory Bourdy and Soomin Lee were also three shots off the lead alongside Lucas Bjerregaard, Bernd Ritthammer and Martin Wiegele.
