Spurred by a double-eagle on the par-5 12th, Lomas shot an opening round 6-under-par 66 at the Centenary course on Thursday.
He is tied with Mark Mouland, who was 6-under through 13 holes before darkness set in and forced play to be halted.
On a day which began with a three and 1/2 hour delay due to heavy fog and mist, Lomas and Mouland ended in the lead by one stroke over four players, including Warren Bennett, Stephen Gallacher and Justin Rose, who all finished with 67. Australian Peter O'Malley also made it to 5-under through 15 holes.
Meanwhile, two shots off the pace is none other than European captain Sam Torrance, who went around in just 68 strokes Thursday.
As his own game is shaping up nicely, Torrance might well have noticed the efforts of Bennett and Rose as well, as they sit respectively at Nos. 22 and 26 on the points list.
Bennett has especially displayed solid form of late, as the one-time winner on the European Tour finished second in the Dutch Open, when he lost in a playoff to Bernhard Langer, and then ended in a tie for fourth at the Volvo Scandinavian Masters.
Thursday, he added an eagle-three at the par-5 9th to three other birdies for 67.
Two other European players in the hunt for the Ryder Cup are Scotlands Andrew Oldcorn and Andrew Coltart.
At No. 13 on the list, Coltart stayed right in contention with a first-round 71, while Oldcorn ' No. 14 ' went one better with a 2-under 70.
Full-field scores from the Gleneagles Scottish PGA Open