From Longman Dictionary of Contemporary Englishstroke of luck/fortunestroke of luck/fortuneLUCKYsomething lucky that happens to you unexpectedly In a stroke of luck, a suitable organ donor became available. → stroke
Examples from the Corpus
stroke of luck/fortune• I also had a stroke of luck when a Jehovah's Witness called at the door earlier.• Then I had a stroke of luck.• That, it turned out, was a stroke of luck.• True enough, you married him, and what a happy stroke of fortune for the candidate.• But by a remarkable stroke of fortune we were saved from falling into error.• But, in a strange stroke of luck, this fall occurred as Maximilian and his armies were approaching Ensisheim.• The years of work and attention were bearing fruit now, and suddenly this stroke of luck with Betty. 