In his eighth start of the season, 18-year-old Fagundez scored his four goal of the year, doubling his previous season best.
The goal came in the 23rd minute. Chris Tierney beat Matías Laba along the left touchline and swung a heavy cross into the box. At the far post, Diego Fagundez met it before it could land, slamming a half-volley in off the turf.
Fagundez has now scored three goals in three matches.
Juan Agudelo, who joined in a trade from Chivas USA ealier this month, scored deep into stoppage time of his first start for the Revs.
Toronto's winless streak stretched to 10 matches, leaving the Canadians on seven points.
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