DOHA, Qatar - Top seed Caroline Wozniacki defended her No.1 ranking with aplomb on Friday, fending off former WTA World No.1 Angelique Kerber, 7-6(4), 1-6, 6-3, to reach the semifinals of the Qatar Total Open.

"Angie is in such great shape, so I knew it would be an even playing field heading into the third set," Wozniacki said during her on-court interview. "I got a little bit lucky because I felt we both played well for big periods of the match. I'm sure she'll have a great year going forward, but I'm happy I got the win today.

"My goal is just to enjoy the game and have fun out there, and stay healthy. I've achieved it, won in Melbourne, which was a huge goal for me and something. It's something I'm really proud of, but nothing I'm thinking about too much."

Wozniacki captured her maiden major title and clinched a long-awaited return to No.1 over Simona Halep in the finals of last month's Australian Open, but Halep was in with a chance to reclaim the top spot had she finished the week in Doha one round farther than the Dane. Following Halep's straight-set win over Catherine "CiCi" Bellis, the Romanian was forced to withdraw due to the lingering foot injury she's dealt with since Melbourne.

"Obviously I feel really bad for her. She looked like she was moving well out there, but she's a great player, and a great champion. I hope she'll be back out there soon."

Still, Wozniacki needed to beat a resurgent Kerber, a former Australian Open champion who looks like she will very much be in the hunt for the No.1 ranking as the season wears on, shaking off a disappointing 2017 to start 2018 with the Apia International Sydney title and a run to the semifinals Down Under.

Kerber and Wozniacki have played a whopping 13 times, but hadn't met since the 2016 US Open semifinals, a match the German won to, ironically enough, become No.1 for the first time en route to her second Grand Slam title.

As the opening set got underway, Kerber got out to a much faster start than she had against Johanna Konta in the previous round, breaking serve in the third game and holding on for a 5-3 lead before Wozniacki dug in her heels to level proceedings.

"I feel like I had a lot of chances in the first set to win a lot of the games that I ended up losing," Wozniacki said after the match, "and then she had a chance to serve it out and win the set, and I somehow came back. So I feel like playing the tiebreaker to decide the set I thought was fair after that."

The Dane held a set point ahead of the ensuing tiebreak and kept the momentum to grab the opening set from her friend and rival. 

Undeterred, Kerber immediately turned the tide to take the second set in decisive fashion and break to open the third.

"I think I played very aggressive and played well in that tie-break and then second set she played very well. I made some unforced errors going for a little too much but she played really well. And third set, again, she had a chance in the beginning to go up 2-0, and I managed to just stay tough, and it could have gone either way really."

Wozniacki broke straight back in a marathon game and defended her serve in impressive fashion as fatigue began to set in for Kerber, particularly after some long rallies at the match's conclusion. After a grueling two hours and 20 minutes on Centre Court, Wozniacki served out the win, striking 46 winners to 29 unforced errors. 

It was a high-quality affair all around as Kerber maintained a positive differential as well, hitting 37 winners to 30 unforced errors and will leave Doha knowing she even won one more point than Wozniacki - 108 to 107 - something that should fuel her competitive fire as the season continues. 

"It was a good match, but I lost," a disconsolate Kerber said after the match. "Of course, I'm disappointed, but I tried my best. She played good in the important moments, and I gave what I could tonight. It was a good match from both of us. I have to sit down, relax, and think about the last two matches here. Then I'll look forward to the next tournament."

Wozniacki will next play either Petra Kvitova, who advanced after Julia Goerges was forced to retire due to a hip injury, for a spot in the final.

"The fans are great; they always support me here. I'm so glad they come out and make this tournament special."