MOSCOW, Russia -- Lucky loser Olga Danilovic of Serbia set up an all-teenager final at the Moscow River Cup on Saturday with a stirring three-set upset of No.5 seed Aliaksandra Sasnovich of Belarus, 6-2, 5-7, 7-5, advancing to the first WTA final of her career.

"I think I played very well, especially in the difficult moments," Danilovic told the press, after her victory. "I knew that I had a very tough opponent, so I didn’t give myself space to go with up and downs. I knew that if I go with ups and downs, I’d have nothing to do on the court."

The 17-year-old left-handed Serb lost in the final round of qualifying to Paula Badosa Gibert on Monday, but finds herself in the championship match after a topsy-turvy match against Sasnovich, ultimately prevailing in two hours and 19 minutes.

The high-octane game of Danilovic paid off once again this week, as the hard-hitting youngster fired 42 winners, more than her 39 unforced errors during the encounter. Sasnovich's 20 winners were undone by 36 unforced errors throughout the match.

Danilovic will now face fellow 17-year-old Anastasia Potapova of Russia, who also moved into her first WTA final earlier on Saturday, when Tamara Zidansek of Slovenia retired due to illness while trailing in the third set of their semifinal.

"Today, the crowd was amazing, they were cheering for me like I’m one of theirs, so it’s very nice," said Danilovic. "Tomorrow, it’s [Potapova's] club here. I cannot say nothing -- if they were to come to Serbia, they would probably cheer for me that way."

At the start of the match, the powerful groundstrokes by the young Serb routinely forced errors from Sasnovich, leading to the first break of the match for a 2-1 lead. Danilovic exhibited exceptional mental toughness for her age in the very next game, fending off three break points to hold for 3-1.

Later, multiple winners brought Danilovic to double break point at 4-2, and Sasnovich handed over a second break with a double fault. The Serbian teen quickly closed out the first set in the next game. It was a dominant opening frame by Danilovic, who raced to the one-set lead behind 13 winners to only seven unforced errors.

Danilovic continued to be the aggressor at the outset of the second set, cracking service returns with verve to claim a break of serve and lead 1-0 after her fourth break point of the game. But Sasnovich kept her cool, and finally took advantage of a weak service game by Danilovic -- the Serb fired four double faults in the 2-1 game, allowing Sasnovich to get level in the set.

Once the Belarusian achieved balance in the second set at 2-2, she seemed to relax, and improved her defense, cut down her unforced errors, and moved forward to finish points off more effectively. Danilovic continued to hit powerful winners with aplomb, but Sasnovich’s service games were no longer a weakness, and the combatants moved to 5-5.

After Sasnovich held for 6-5, Danilovic faltered when serving to stay in the set. The Serbian lucky loser hit a couple of miscues before Sasnovich’s stellar defense caused Danilovic to shank an overhead well long on the Belarusian’s second set point of the game. The match was tied at one set all, after Danilovic fired 16 unforced errors in the frame, to Sasnovich's 12.

Danilovic did not initially succumb to the pressure of a decider, claiming the first break of the third set at 1-1 by pummeling forehands at Sasnovich until the Belarusian hit a backhand long. Serving at 2-1, Danilovic again steeled herself when the chips were down, staving off five break points to hold and take a 3-1 lead.

The Serb clinched another break to lead 5-2 and serve for the match. There, Sasnovich claimed one break back, blasting a forehand return winner to take the game, and consolidated that break to reach 5-4. Danilovic served for the match a second time, but once more, inexperience caught up with her, and she hit a number of forehand unforced errors to drop serve again.

Sasnovich had pulled herself all the way back to 5-5, but could not take advantage of this comeback, as deep, heavy hitting by Danilovic gave the Serb another break and a third chance to serve out the encounter. This time, Danilovic would come through, forcing a final Sasnovich error with a huge forehand to enter her maiden WTA final.

"When it was 5-2, I think I got tight," Danilovic admitted. "She played amazing points -- we had very good rallies, she handled them better than me. So at 5-5, I just said, ‘Okay, there is no fourth set or fifth set, this is the one, I have two more games.’ I gave my best, I gave everything I had, and it was good."