Raonic defeated the top-ranked American in three sets, 6-7(12), 7-6(4), 6-3, despite it being just the Canadian’s fifth match since 2021.
Playing on home soil for possibly the last time before retirement, Raonic, once the third-ranked men’s singles player in the world, showed he is not done yet.
The Thornhill, Ontario native, now ranked No. 545, bounced back from a controversial first set tiebreak loss to win the best-of-three match over Tiafoe, moving on to face Taro Daniel in the second round on Wednesday.
Raonic is a -163 favourite to defeat Daniel.
With Tiafoe up 13-12 in the first set tiebreak, Raonic’s shot clipped the top of the net and popped in the air. The American got there in time to fire a cross-court winner, but his momentum carried him into the net.
Typically, making contact with the net means that player loses the point, but this was not the case on Monday night.
Instead, after a lengthy review, it was ruled he ran into a ‘permanent fixture’ of the net and would be awarded the point, and subsequently the first set.
"I don't have faith that they were being completely honest, but it is what it is,” Raonic said after the match, per EuroSport. “… and I think that just gave me some momentum and some force going forward.”
That it did, and the Canadian never looked back, taking the second and third sets to win the match. Raonic recorded 37 aces, one short of his three-set record of 38 achieved in 2011.
It was a monumental upset when considering the world rankings and what Raonic has been through since we last saw him on the world stage.
The 32-year-old has hardly played tennis since suffering Achilles and toe injuries in the summer of 2021.
He did not play a match or hit a single tennis ball for 14 months before returning to action in June 2023 at the Libema Open.
Raonic then participated in Wimbeldon last month, the site his best ever Grand Slam finish (runner-up in 2016 to Andy Murray), where he fell to Tommy Paul in the second round.