In addition to Lukaku’s goals, one on the stroke of half time and the other, the other 12 minutes into the second half, Kevin De Bruyne added a third goal in stoppage time. The full-strength Belgium side, who top the FIFA rankings, dominated the Scots from the start.
Nevertheless De Bruyne, Eden Hazard and their teammates were unable to make a breakthrough until right on halftime, when Hazard scooped the ball up in the air from the by-line for Lukaku to head home.
The Manchester United striker then netted his 48th international goal as he followed-up a shot by De Bruyne that was parried into his path by Scotland goalkeeper David Marshall in the 57th minute.
Lukaku also put two efforts narrowly wide as he went in search of his hat-trick while Scotland could have pulled one back on a rare counter attack in the 85th minute.
Yet even with Belgium keeper Thibaut Courtois out of position, the ball got stuck between the legs of first Ryan Fraser and then Oliver Burke and the opportunity was lost.
After four games Belgium top Group I with 12 points, this is three points more than Russia, who have 9 points.