Canadian teenager Denis Shapovalov shocked top seeded Rafael Nadal to reach the quarter-finals of the ATP Montreal Masters tournament, spoiling the Spaniard's chances of returning to world number one.

The 18-year-old Shapovalov continued his giant killing form at the hardcourt tournament by rallying to stun Nadal in three sets 3-6, 6-4, 7-6 (7/4) on Thursday.

"I was just swinging for the fences," said Shapovalov, who needed a wild card to get into the tournament.

The 31-year-old Nadal would have returned to No. 1 in the world if he reached the semi-finals.

But Nadal struggled to get the ball to Shapovalov's backhand and didn't have an answer for the Canadian's blistering forehand winners.

"He played well. He has great potential," Nadal said. "I wish him the best. He played with the right determination."

Shapovalov's biggest win of his young career against the 15-time Grand Slam winner came as a result of some inspired tennis in front of a boisterous home crowd who cheered his every shot.

Shapovalov, who is ranked 143rd in the world, had just three wins this season coming into the tournament. He quickly got on a roll in Montreal, beating Brazil's Rogerio Dutra Silva in the opening round 4-6, 7-6 (10/8), 6-4. He then defeated former US Open winner Juan Martin Del Potro in the second round in straight sets 6-3 7-6 (7/4) to set up the showdown with Nadal.

Shapovalov fell behind 3-0 before winning seven of the final eight points of the third set tiebreaker. He closed out the match with a forehand winner down the line and celebrated by falling onto his back then covering his face with his hands.

Nadal easily won the first set but couldn't put the free-swinging Canadian away with a second set victory.

The third game of the second set lasted 14 minutes with Shapovalov finally holding serve when Nadal's volley sailed into the net. Shapovalov managed to win the game despite double faulting three times.

"Was it only 14 minutes?," Shapovalov asked. "It felt like three hours. 

"I just kept fighting. I knew it was going to be really tough. I went for my shots in the big moments and I caught a couple of lines got a little bit lucky but at the end of the day that is what tennis is."

Shapovalov said he didn't think he had a chance to win at all before the match. It wasn't until he levelled the sets at one each that he realized he could beat the 10-time French Open champion.

"The whole day I was like - there's no chance. I will go and have fun but there is no way I am beating this guy," Shapovalov said.

"I went up a break in the second set early and even though he broke me back I felt like - OK, I am capable of breaking him.

"So when I won that second set I thought let's go one more set and who knows, anything can happen."

Shapovalov blasted a total of nine aces, including some on his second serve. He also had seven double faults and won 67 percent of his first serve points.

- 'Dream come true' -

"It is incredible. I can't even talk right now. I grew up watching Rafa so just to be able to compete with him is one thing but to come out winning is a dream come true for me."

Nadal won 77 percent of his first serve points, but had just two aces and six double faults in the two hour, 45 minute center court match. 

Elsewhere on Thursday, Roger Federer maintained his career-long winning streak over David Ferrer to advance to the quarter-finals after a three-set battle with the veteran Spaniard.

Federer, 36, had never lost in 16 previous meetings with the 35-year-old Ferrer, whom he first defeated 14 years ago at the Vienna Indoor tournament.

But while Ferrer managed to take the opening set -- ending Federer's 32-set streak -- the Swiss ace raised his game to win 4-6, 6-4, 6-2.

"I actually feel really happy because I know I can play a lot better. David can play a lot better, too," Federer said. 

"We battled, both tried to find a way to win. You know, he had a good start, I had a better finish."

In other matches Thursday, Germany's Alexander Zverev defeated Nick Kyrgios 6-4, 6-3, Roberto Bautista outlasted Gael Monfils 4-6, 7-6 (7/5), 7-6 (7/2) and Kevin Anderson of South Africa cruised past Sam Querrey 6-4, 6-1.

Source: AFP