DOHA, Qatar - Unseeded Elise Mertens reached the biggest final of her career on Friday at the Qatar Total Open, as she outlasted former World No.1 Angelique Kerber in a three-set semifinal, 6-4, 2-6, 6-1.

The Belgian, winner of four WTA titles in her career to date, moves onto her sixth career WTA final and will face another former World No.1 in Simona Halep, who rallied from 4-1 down in the final set to defeat Elina Svitolina in a stunning first semifinal.

The final will be Mertens' third straight match against a Top 10 player this week, as the former World No.12 also defeated No.5 seed Kiki Bertens in the quarterfinals earlier this week.

"I knew it was going to be a really difficult match to play. I mean, I had to play aggressive, stay on my line, because she can put that one ball back in the court," Mertens asssessed.

"I'm really happy that I won the first set, because the game I played I think was good. Second set, she found solutions. It was still pretty close, but, the third set was just a refresh, I started back again, and played more aggressive than the second set, stay more on the line.

"I think my service really helped me today, also, that first percentage in the court and make some balls."

The Belgian was quick out of the gates in the first set in the first career meeting between the two players, as she built a 4-1 lead only to see the defending Wimbledon champion rally for parity at 4-4.

Nonetheless, Mertens held her nerve and edged a pair of tight games to take a one-set lead, and rebounded in style with an emphatic decider after losing the last four games of the second set. 

From 1-1, after Kerber held and saved a break point in the process, the 24-year-old won the last five games of the match in style, which included a sprint through nine of the last 10 points overall.

"Tennis is full of surprises. I think women's tennis is really close to each other. Everybody is a great competitor, works hard. So I'm really happy that I got the win today," said Mertens.

"I think, especially once you have been [to a final], you know the nerves, but of course you know what you can do, and I have to feel confident. I feel confident because, you know, I had a great match today.

"Of course Simona has a lot of experience, too, so it's going to be a difficult one."

Mertens lost both meetings she played against Halep in 2018 in straight sets, winning just six games combined.

"I think I can play loose. I have to play relaxed, because then you know if you play at your best. I have to play aggressive, but not too much. She can bring a lot of balls back, but I'm mentally prepared for tomorrow," she added.

"I just look at round per round, and I look at the opponents. I am trying to not look too much on I'm in the semis and the final. Of course you know, but I think it's important to just stay focused and try to play your game.

"It didn't really come together in Australia. Of course, not bad results but not the way I wanted it, but in tennis, every week there is another tournament, so every week you can improve yourself."