BEIJING, China - In a much-anticipated and riveting first clash between the two most recent US Open champions, No.4 seed Naomi Osaka fought back from a set and a break down in both second and third sets to take the honors 5-7, 6-3, 6-4 over No.5 seed Bianca Andreescu in two hours and 14 minutes to reach the China Open semifinals.

"It meant a lot because I feel like people counted me out after the Europe thing," Osaka said afterwards, referring to her clay and grass swings in which she did not reach a final. "I'm just like, I still won a slam this year, I won [Osaka]. I'm still here. But there's a sort of beauty to be underrated."

The result ends Andreescu's winning streak, dating back to the fourth round of Miami in March, at 17 - but extends Toray Pan Pacific Open champion Osaka's own to eight in this year's Asian swing. The Japanese No.1, who struck 31 winners to 30 unforced errors and 10 aces, has also dealt out Andreescu's first defeat at the hands of a Top 10 opponent in nine matches.

"I forgot how it feels [to lose]," said Andreescu. "Honestly, it sucks. I didn't miss it at all. But at least I didn't get whooped 1 and 1. I put on a fight. Honestly, it could have went either way. It was just some points here and there. At the same time I am pissed, but at the same time I'm proud of myself with how I played today. I really fought, especially in that last game. Holy crap, that was crazy."

Both players also admitted that they had been aware of the chatter around the matchup and that it had affected them - albeit in different ways, with Osaka revealing that it had made her "really nervous" while Andreescu asserted that she had been "more focused than usual". As Osaka noted: "We're both, in a way, kind of different from each other."

Those differences extended to their game styles, too. Initially, the Canadian's competitive edge was fully on display as she probed relentlessly at the Osaka serve. Despite the Japanese No.1 winning 78% of her first serves today, Andreescu's relentlessly aggressive approach to returning the second serve limited her to only 31% of those points and meant that holding, even with a lead, was rarely straightforward: Osaka was broken from 40-0 up in the first game, 40-30 up in the fifth, and 30-0 up in the penultimate game of the set.

Andreescu, meanwhile, was also deploying her full repertoire off the ground, breaking up the rhythm of rallies with biting slices before injecting sudden pace to take control. Forced by the 19-year-old's supreme anticipation into going for the lines, Osaka lapsed repeatedly into error and quickly fell behind 5-1.

"I feel like in the beginning we were just coping each other out," mused Osaka. "I could not find the mental line of not being nervous and also being fired up. That was a bit of a struggle. She was probably thinking,, Wow, what is she doing?... Wow, she won two Grand Slams like that?"

Andreescu seemingly having an answer to everything Osaka threw at her was also an issue. "Of course I've watched her play on TV, but it's so different from actually playing against her," said the Australian Open champion. "I know that she is incredibly smart. She knows when the rally isn't working out for her, when to change it up and make it difficult for the other person. So just to experience that in person was very frustrating.

"But also I think for me, my game plan going in was to just be the more aggressive player. I can't be the defensive one. Just trust myself, trust my serve, be aggressively consistent until I have the shot."

That game plan came into its own as the set began to take a turn for the scenic when Andreescu, serving at 5-2, 30-15 and in full control of a rally that would have given her two set points, attempted a dropshot to finish it off - only to send it into the net. Suddenly, momentum shifted as Osaka sensed an opening door: hitting her spots as Andreescu's forehand deserted her, the Australian Open and Osaka champion roared back, levelling at 5-5 as Andreescu offered up a second double fault.

But while many of the reigning US Open' champion's matches over the course of her winning streak have been marked by dramatic scoreboard fluctuations, it has rarely mattered in the end. As in the final at Flushing Meadows, where Andreescu saw Serena Williams fight back from 1-5 to 5-5 in the second set, the teenager simply gathered herself to take the set anyway. At 5-5, 30-30, Andreescu won a brilliant battle of forehand angles en route to reeling off the last eight points of the opening act, making no mistake serving for it the third time.

If anything, the start of the second set saw the Indian Wells and Toronto champion become even more daring and creative in her patterns of play - and her ability to make bold and correct split-second decisions mid-rally. Curving, sidespun forehands were followed by booming backhand winners; when a deep return elicited a weak reply from Osaka, Andreescu was quick to dart into net to put it away. A crucial tussle in the third game was eventually captured by Andreescu on her fourth break point with a clever wrongfooting forehand.

However, the 2018 US Open champion would not be quelled so easily. Storming the net herself after booming returns, Osaka found a series of backhand bangers to test Andreescu again in the sixth game - and would level as the Auckland runner-up coughed up a double fault. This time, Osaka kept her foot firmly on the pedal to take 14 of the last 16 points of the set.

Not only did last year's semifinalist enter a zone on serve, with Andreescu barely able to lay a racquet to Osaka's deliveries, but she also peaked defensively: serving at 3-4, Andreescu dictated every point, only to be undone  by an errant drive volley of her own - and two remarkable winners off the back foot from Osaka, a reflexed pass and a pinpoint lob, both worthy of the great Agnieszka Radwanska.

As the contest entered its deciding set, both competitors would bring out some of their finest tennis as the quality rose even further. Both were problem-solving their opponent's adjustments in real time, and consequently the momentum continued to shift unpredictably. Andreescu, demonstrating fine touch at net, struck first to take a 3-1 lead - but another breathtaking backhand winner down the line from Osaka garnered the break back immediately.

That shot would prove to be key for Osaka as she battled towards the finishing line, winning her another break for 5-4 - and then, in a dramatic final game, having squandered one match point with a double fault and a second with an erroneous challenge, to carve up a third chance. This time, Osaka made no mistake. The first serve had been crucial to her success over the course of the match - and an unreturnable one down the tee would seal a magnificent victory.

Afterwards, Andreescu was already looking ahead to their next encounter. "I think we're going to have many matches like this" she predicted. "Our game styles are pretty different, but they level up pretty equally."

Osaka was not quite as keen - "Listen, I don't want to play her any more, I'm good, one-and-done," she joked - but accepted that this clash could be the start of a special rivalry. "It's bound to happen again," she said. " I like seeing the younger players. I really love seeing Coco [Gauff], Iga [Swiatek], her do well. It gives me a lot of motivation, makes me think like they're younger than me so I should be able to do the things they're accomplishing."