The hard-serving 21-year-old from Thornhill, Ont., lost 4-6, 6-3, 7-6 (7-5), 6-3 to Australia's Lleyton Hewitt in third-round-play Saturday, failing to match his impressive run at last year's tournament.
After winning the first set, Raonic fell victim to Hewitt's legendary determination in a match that lasted just over three hours.
"He played quite a bit better than me and it showed," Raonic said. "He was more steady, more constant the whole match. I was more up and down. It's unfortunate in a way because I felt like I had the ability to win, but I just didn't do it."
Raonic said he will take the loss in stride and look make adjustments in his game.
"I'm only going to keep learning. As much as I hate to really look at anything positive out of today, it's a learning experience. There's so much to take from it."
The showcase match was a triumph for the 30-year-old Hewitt, the 2005 finalist at his home Grand Slam.
"He's a tough player," said Hewitt. "There are not that many opportunities to break his serve. I was getting bombarded on his serve, but you have to forget about it and move onto the next point when one comes by you at 226 kilomtres per hour.
"He played his best tennis when he was down."
Raonic, the No. 23 seed at this year's tournament, became a celebrity back home after making a breakthrough at last year's Australian Open.
He made it through qualifying before winning three straight matches to advance to the fourth round. Less than a month later, the youngster was holding up his first career trophy at San Jose.
Raonic began this season with a title in Chennai, India, but came up short against the vast experience of two-time Grand Slam winner Hewitt, playing in his 16th Open.
He learned a lesson in pressure tennis as Hewitt fought back to earn the victory in his first match with the Canadian.
"I'm probably just a little stubborn at the moment now and I won't listen really to too much," Raonic said. "But when the time comes, I'll open up my ears, I'll learn from it and hopefully be better next time.
"I started out nervous, I struggled more with him than I did with anything else really."
Raonic, who will now concentrate on Canada's Davis Cup first-round tie next month in Vancouver, finished with 23 aces but 52 unforced errors. He came to the court with a six-match win streak.
He won the first set before Hewitt, almost a decade older, found his rhythm. The Australian broke for 5-2 and served out the second set to level at a set each, then claimed the third in a tiebreaker after Raonic saved two set points.
The final game for the third set was tight, lasting for four deuces with Raonic saving a pair of match points before Hewitt smashed an overhead for a third chance. He then lobbed a shot over Raonic to take a 2-1 lead.
The former No. 1-ranked Hewitt, who hasn't won a major since Wimbledon in 2002, entered the tournament on a wild card after slumping to a ranking in the 180s during an injury-marred 2011.
Despite his experience — he has played 50 previous Grand Slam tournaments and this Australian Open campaign beats the record of 15 held jointly by Jack Crawford and Harry Hopman — Hewitt had difficulty closing out Raonic.
He needed three match points to serve it out, and had to save two breakpoints in the process as Raonic went for everything to stay in the match.
"It's tough serving out any match. A couple of months ago I would have done anything to be in this position, serving to go into the second week at the Australian Open," said Hewitt, who will be 31 next month. "It's just a game, but it's a big bloody game."
Hewitt's next opponent will be his toughest yet: defending champion Novak Djokovic.
Djokovic won the Australian title last year during a 41-match winning streak at the start of the season. The 24-year-old Serb won three of the four majors and finished the year at No. 1, surpassing both Rafael Nadal and Roger Federer.
"Obviously, he's the best player in world at moment, he's there for a reason," Hewitt said. "What he did last year was amazing. I'm going to have to come out here, take it to him, see what happens."
In men's doubles, Toronto's Daniel Nestor and Belarus partner Max Mirnyi dispatched Colombians Juan Sebastian Cabal and Robert Farah 7-6 (7-0), 6-2 on Saturday to move into the third round of the Australian Open.
Nestor and Mirnyi were dominant and earned the victory in just under 90 minutes with a combined five aces. They won all 10 of their service games while breaking the South Americans twice from four chances.
The 39-year-old Nestor and his partner are seeded second in the doubles field behind Americans Bob and Mike Bryan, their longtime rivals. They will next take on Italians Potito Starace and Daniele Bracciale.
Nestor and Mirnyi reached the semifinal at Melbourne Park in 2011, with Nestor and his former partner Nenad Zimonjic of Serbia playing the 2010 final.
Nestor's mixed doubles hopes ended before they began as injured partner Maria Kirilenko withdrew with a thigh injury before their opening match.