Britain was lucky to get into the Davis Cup quarter-finals, while Spain went past Croatia to advance and defending champion Argentina battled Italy into a decisive fifth match at a rain-hit tie.
Canada's Denis Shapovalov hit chair umpire Arnaud Gabas in the face with a ball and was defaulted in the deciding match, handing Britain's Kyle Edmund a 6-3 6-4 2-1 triumph and giving Britain a 3-2 victory in the first-round tie at Ottawa.
"It was a strange way to finish," Edmund said. "I've never been part of something like that."
Shapovalov, a 17-year-old Israeli-born Canadian, apologized to Gabas in the referee's office as the umpire was being treated for bruising and swelling of his left eye before being taken to a nearby hospital.
"No one is nicer or carries themselves better for a 17 y/o than Shapovalov," Canadian teammate Vasek Pospisil tweeted. "Everyone can see that today was an accident."
Pospisil had blasted 25 aces in a 7-6 (7/3) 6-4 3-6 7-6 (7/5) victory over Dan Evans to level at 2-2 for Canada, which was without injured world number four Milos Raonic.
Britain won Saturday's doubles match. Edmund lost to Pospisil in Friday's singles and Shapovalov fell to Evans.
"It's a shame that it has happened that way and I feel for the young lad because he's a great talent and he has learned a harsh lesson today," British Davis Cup captain Leon Smith said. "I thought Kyle, from what we saw Friday to the way he came out today, he was absolutely fantastic."
Britain, the 2015 champions playing without top-ranked Andy Murray, advanced to a quarter-final matchup April 7-9 against France with that winner facing either Spain or Serbia in a September semi-final.
Spain's Pablo Carreno Busta swept Croatian journeyman Nikola Mektic in straight sets to clinch a 3-2 victory and set up a mouthwatering quarter-final clash with Novak Djokovic's Serbia.
Carreno Busta defeated world number 319 Mektic 7-6 (7/4) 6-1 6-4 in the deciding rubber in Osijek as five-time champions Spain rallied from a 2-1 overnight deficit to knock out last year's runner-up.