The France international took his remarkable tally for the campaign in all competitions to 26 with a stunning strike in the 78th minute.
Lyon open to Lacazette exit - Aulas
Metz, who found themselves on the wrong end of a 5-0 hiding, could not contain the in-form frontman once he got a sight of the target.
Twisting and turning inside the box, once a yard of space opened up, Lacazette curled a spectacular effort into the top corner.
Lacazette reveals Barcelona dream
With the 25-year-old proving to be unplayable at times this season, it is easy to see why he continues to generate plenty of transfer talk.
Arsenal are known to be long-time admirers of Lacazette, while La Liga heavyweights Barcelona and Atletico Madrid have also been mooted as possible destinations for the talented frontman this summer.
