SHENZHEN, China - In the first-ever meeting between two of this season's Grand Slam champions, Simona Halep got the better of Bianca Andreescu.

The Wimbledon champion saved a match point to edge the US Open winner, 3-6, 7-6(6), 6-3, in the second match from the Purple Group at the Shiseido WTA Finals Shenzhen, joining Elina Svitolina as a winner on Monday in round robin play

"It's been a great match both sides, in my opinion. She did great this year. Winning so many tournaments gave her a lot of confidence. I expected a very tough match," Halep, contesting her first match since the China Open, said. 

"I'm really proud actually that I could fight in this way because I have a month that I didn't really practice with my back, with the injury. But looks like I'm still there.

"Today, it was a challenge because she's 10 years younger than me. It was a good fight. I'm happy about my victory."

The Canadian won four straight games to pocket the opening set, and twice came from a break down in the second set to put herself in pole position to win her debut match at the season-ending tournament, holding a match point on Halep's serve in the 12th game of the second set. 

"I think I was executing the right tactics. My serve. My return was good today, for most of the match at least. I didn't feel intimidated at all stepping on the court," the Canadian said after the match.

"I know I looked up to her a lot, so being able to play her was really fun. Yeah, maybe I'll get to play her again here, get my revenge.

"It was a good match. She fought really hard. I didn't take my chances in the second set, so I'm really disappointed about that."

In photos: Story of the Purple Group: Svitolina and Halep begin with victories

Halep forced a backhand error from the Canadian to close a long rally en route to holding serve, and kept the dramatic clash alive by winning a second-set tiebreak in extra points, after holding leads of 3-0 and 6-4. 

"She changes a lot the rhythm, with some slices that you don't really expect them. I think at the match point I've been aggressive with the backhand down the line, if I remember well," Halep continued.

"I didn't think that I can lose the match [at match point]. I just wanted to start, even if could have been too late, to start to hit the ball and go down the line. I think today it was a good shot against her."

The Romanian's comeback efforts weren't done from there, either: despite being the first player to lose serve in the decider, being broken in the third game to trail 2-1, she ultimately won five of the last six games to seal victory in two hours and 34 minutes, over an hour after Andreescu held match point. 

As It Happened: How Halep engineered comeback epic to edge Andreescu

"In the second set, even if she was leading, I had a thought that I'm stronger mentally. We had some long rallies, and I won those balls," Halep said.

"Then I just didn't think about the result. I've been focused on myself. I just had in my head what I have to play against her to be good."

Treated for a back injury late in the match, the 19-year-old nonetheless earned, but could not convert, any of the three chances she held to extend her third-set lead to 3-1, and the Romanian quickly charged through her opening to win the next three games, flipping a 2-1 deficit into a 4-2 advantage.

"She started putting more balls in the court, first of all. Then in the third set, I really don't want to blame my back, but I felt like I didn't have the same power as I did in the first and second set," Andreescu added.

"But I fought well with what I had in the third. I'm proud of that. Still pretty disappointed."

Andreescu continued to battle and got the final set back on serve, but relentless counterpunching from Halep proved to make the difference in the end.

From 30-30 on the Canadian's serve in the penultimate game, Halep won the last six points, and emphatically sealed the comeback with her first, and only, love hold of the match. 

Needing three sets to seal her victory, Halep now sits behind Svitolina in the Purple Group, after the Ukrainian beat Karolina Pliskova in straight sets to begin Monday's play.

The Romanian evened her head-to-head against Svitolina at 4-4 over the course of this year, winning both matches the pair played - including a 6-1, 6-3 win in the semifinals at Wimbledon

"[It] looks like she likes the court. She feels it. She has confidence on this court. She won last year. It's a great thing to win this tournament because it's like playing the final of a Grand Slam every day," Halep said. 

"It's going to be a tough match definitely. I'm looking forward to it. But first I will enjoy the day off tomorrow. I try to recover and then we will see. But I'm ready to fight again and I'm happy to be in this position."