Austrian third seed Dominic Thiem was on the receiving end of an upset at the Rogers Cup as David Goffin, Pablo Carreno Busta and Jack Sock booked their spots in the second round.
Thiem was unable to close out the second-round win against Diego Schwartzman, beaten in three sets in Montreal on Tuesday.
There was no such trouble for fellow seeds Carreno Busta, Goffin and Sock, who saw off Yuichi Sugita, Karen Khachanov and Pierre-Hugues Herbert respectively.
Borna Coric earned a meeting with top seed Rafael Nadal, while Denis Shapovalov emerged from the clutches of defeat.
WASTEFUL THIEM BUNDLED OUT
He had four opportunities to advance but on all four occasions Thiem was thwarted by Schwartzman, who completed a stunning 4-6 7-6 (9-7) 7-5 upset.
The Argentinian saved four match points after rallying from 5-2 down in the final set.
Schwartzman won the last five points of the match to send Thiem - who tallied 67 unforced errors - packing at the first hurdle.
GOFFIN, CARRENO BUSTA AND SOCK WIN THROUGH
Goffin - the ninth seed - dug deep against Japan's Sugita, surviving 4-6 6-1 6-4.
The Belgian did not have it all his own way as he looks ahead to Chung Hyeon, who upstaged Feliciano Lopez 6-1 4-6 7-6 (7-3).
Spanish 11th seed Carreno Busta prevailed against tournament debutant Khachanov 3-6 6-3 6-2.
American 15th seed Sock, meanwhile, won 7-6 (7-4) 6-3 against Herbert.
CORIC SET FOR HUGE CHALLENGE
Coric will face tennis icon and 15-time grand slam champion Nadal in the next round after easing past Mikhail Youzhny 6-2 6-4.
The 20-year-old Croatian claimed just his second win in three appearances at the Rogers Cup.
SHAPALOV SAVES FOUR MATCH POINTS
Former junior world number one Shapovalov, 18, came back from the brink to trump Rogerio Dutra Silva 4-6 7-6 (10-8) 6-4.
Shapovalov saved four match points to somehow avoid defeat against the Brazilian.
His reward is a showdown with Juan Martin del Potro, while Sam Querrey and Kevin Anderson were among the winners elsewhere.
BODY BLOW FOR BERDYCH
Tomas Berdych was due to take on Nikoloz Basilashvili but did not take to court due to a rib injury.
"I am sorry I have to apologise all my Montreal fans," Berdych posted on Twitter. "I couldn't play because of my rib dysfunction. I need to get well to go to [the] office soon!!"
Basilashvili instead took on lucky loser Ernesto Escobedo, who advanced to the second round with a 7-6 (7-4) 6-4 victory.