Peliwo won his second junior Grand Slam title of the year Sunday, beating Britain's Liam Broady 6-2, 2-6, 7-5 in the boys' final at the U.S. Open.
Peliwo, the second seed, fired eight aces past Broady, who had just one in response. Peliwo also limited his mistakes, committing five unforced errors to Broady's 14.
"Won the US Open Jr title today! 6-2 2-6 7-5. So happy to finish my junior career this way. This week has definitely been #beastmode," Peliwo posted to his Twitter account.
The 18-year-old Peliwo also won the Wimbledon boys' title earlier this year, becoming the second Canadian to win a singles Grand Slam title just one day after Eugenie Bouchard of Westmont, Que., won the girls' final.
He also reached the final of the Australian Open and the French Open, making him the first player to reach all four Grand Slam junior boys' finals in the same year since Australia's Mark Kratzmann in 1984.
Peliwo, who will be ranked No. 1 in the world when Monday's rankings are released, will travel to Montreal this week to serve as a practice partner for Canada's Davis Cup team, which is preparing for their World Group playoff tie against South Africa next weekend at Uniprix Stadium.