Ask the players and they'll tell you: the pressure of playing for your country in a Davis Cup tie is different somehow.
Perhaps it's because tennis is, above all else, a 1-on-1 test of will and nerve – even doubles specialists played tournament singles at some level – and playing for a shirt that's not just your sponsor's adds an element of mystique and a sense of mission.
Or maybe it's because nationalism creeps into the equation from both the player and crowd standpoints and the atmosphere is that much more fevered.
Ultimately, it doesn't really matter why, the doing is the thing.
Vasek Pospisil says he found that out last fall, when the Canadian essentially won a road matchup against Israel on his own, taking both of his singles matches and winning in doubles with Daniel Nestor.
"It's a confidence thing, playing for your country is probably the most pressure you're ever going to face on a tennis court. You're not just playing for yourself, you're playing for a lot of people and a team. When you can get through that and have a great Davis Cup moment, you feel almost invincible," said Pospisil, who rode the momentum of his autumn weekend in Israel to a career-high No. 85 ranking on the ATP computer earlier this season. (His form has since tailed off a little, now sitting just outside the top 100.)
The 22-year-old takes to the court at Uniprix Stadium this weekend as part of a Canadian squad that will take on South Africa in a pivotal match-up: the winner advances to the World Group (made up of the top 16 countries in tennis).
The seemingly ageless Nestor, 40, is the top-ranked doubles player in the world and is expected to team with Pospisil in that event Saturday.
The rest of the squad includes Frank Dancevic, a 27-year-old veteran who is expected to play in singles, and the team's undisputed on-court leader, 21-year-old Milos Raonic, the 15th-ranked men's player on the planet.
Raonic hopes to provide a decisive advantage to Canada in the singles matches, which start Friday, the final matches are Sunday.
Beyond this week's on-court action, there is also a bigger picture to consider.
The team entourage this week also includes a pair of Pospisil and Raonic's contemporaries in the emergent generation of Canadian tennis: 24-year-old Peter Polansky and 18-year-old junior sensation Filip Peliwo.
Pospisil said the Davis Cup has been a pivotal proving ground in his development, mostly because of the way the international event has taught him to manage stress.
"You can't let the pressure get to you, you have to be composed and just focus on your game. Davis Cup is the hardest event to do that, to block out all the distractions. If you can master doing that during an event like this, it makes it a lot easier for life on the tour"
Raonic, who missed last fall's tie because of injury and also had to pull out of a World Group against France last spring, said he hopes the Davis Cup will provide a springboard for his own top-10 hopes.
He pointed to the recent example of Spaniard Fernando Verdasco, who reached the semi-finals of the Australian Open a few months after winning the 2008 Davis Cup final, and then broke into the ATP top 10.
"You look at [Serbia's Novak] Djokovic doing the same when they won in 2010, going to No. 1, [Janko] Tisparevic feeding off it. At one point, they had three guys in the top 15. … When you can do these things and do them well, it gives you an intangible," Raonic said.
The rangy, hard-server said there's no substitute for testing oneself in high-profile events – his experience of playing a marathon match against Jo-Wilfried Tsonga of France at this summer's London Olympics is a classic example.
In his apprenticeship in the upper echelons of tennis – and in Davis Cup – Raonic is gaining valuable mental preparation for the crucible that is the late stages of a Grand Slam.
"I felt I dealt with [the Olympics] pretty well. I'm learning constantly, I don't have too many of these experiences under my belt," Raonic said. "I'm just trying to make the most of them and to run with it as much as I can."