Milos Raonic wanted a dominating win Sunday after what he felt was a lax effort two days earlier.

He did exactly that and in dominant fashion, beating Izak van der Merwe 6-2, 6-2, 6-4 to clinch the Davis Cup best-of-five series over South Africa.

The victory secures Canada's spot in the elite World Group, while South Africa is relegated to zone play.

Raonic was happy he won his opening singles match but wasn't pleased with his performance. With the World Group spot in sight, the 21-year-old from Thornhill, Ont., took to the court hungry to finish on top.

"I came out with more of an accomplished goal, other than winning. I came out, did a lot of things well, played on my terms and did what I wanted to do," he said. "The other day I waited for him to lose to me. Today, I played."

Vasek Pospisil won the other singles matches in straight sets Friday, but the Canadians missed a chance to clinch Saturday at Uniprix Stadium when Toronto's Daniel Nestor and Vancouver's Pospisil lost to van der Merwe and Raven Klaasen in doubles.

South Africa entered the tie matches down two of its top players. Kevin Anderson didn't travel to Montreal and Rik de Voest was forced to withdraw on the eve of the tournament with a wrist injury.

"We came here wanting to win but unfortunately things didn't work out the way we planned. Obviously Rik getting injured didn't help our cause," South Africa captain John Laffnie de Jager said. "Two of our top guys didn't play. The team that was here did their best. . .We've just got to keep fighting."

Raonic got off to a quick start Sunday against van der Merwe, breaking the South African in the opening game. His renowned serve was once again his strength, as the 21-year-old held serve in each game of the first set.

"It doesn't inspire confidence when you lose your serve in the very first game. He hit a great shot to break me," said van der Merwe. "He really stepped up his game today, played well and deserved to win."

Raonic's return game helped him stake out a 3-0 lead in the second set, breaking van der Merwe twice in the middle frame. That, combined with ability to hold serve made the World No. 15 tough to take down.

"It's the variety on his serve that makes it very difficult to return against him. There are other people that can serve with force on the tour but he's got the variety. . . and it's very difficult to read," van der Merwe said.

Raonic trailed just once in overall games, van der Merwe picking up the first one of the third set.

As each side held serve in the clinching set, van der Merwe nearly broke the streak in the final game, climbing back from a 40-15 deficit to force a deuce. But Raonic stayed strong for the advantage for the match point.

The Canadian finished the match, which lasted just one hour 45 minutes, with 13 aces and 24 service winners.

It marked a second straight year that Canada won its Davis Cup tie to advance to the World Group, going overseas and defeating Israel. A loss to France put the team back a step in February, leading to the rubber matches against South Africa. But with a good showing under its belt in Montreal, Canadian captain Martin Laurendeau is confident in his team's future.

"Doing it two years in a row shows we belong at this level. We started off great and finished great," he said. "(Winning 4-1) sends a message to other teams that we have a lot of depth.

"When all of our players are healthy and competitive, I think we can take on a lot of teams in the World Group level."

Frank Dancevic of Niagara Falls, Ont., defeated Nikala Scholtz 6-2, 6-2 in the final singles match with the World Group spot already locked up.

Canada will find out its next opponent when the draw is held on Wednesday.