ISTANBUL, Turkey -- Patricia Maria Tig of Romania notched an upset as she moved into her second WTA semifinal of the season, ousting No.2 seed Rebecca Peterson of Sweden, 6-3, 6-1, at the TEB BNP Paribas Tennis Championship Istanbul.

World No.88 Tig had lost their only prior meeting at an ITF Challenger event in Osprey, USA, in 2016, which also came on clay. The Romanian, however, avenged that defeat on Friday, adding an Istanbul semifinal showing to her prior final-four result of the year, which came at Hua Hin in February.

"I played her before, so I knew what to expect," Tig told the press, following her win. "I just fought for every point, and it made me a winner tonight. "

PHOTOS: The story of Istanbul 2020

Tig was down an early break in both sets, but comprehensively stormed back to win six games in a row each of those times and seal the 86-minute victory over 48th-ranked Peterson. The Romanian converted six of her eight break points on the day, while also saving six of the eight break points she faced. 

Tig's run comes just a week after her second-round showing on the New York hardcourts of the US Open, which was her first-ever main-draw match-win at a Grand Slam event, but the quick change in surface has not hindered her one bit.

"I don’t have a problem changing surfaces, because since I was a little girl, I played on many different surfaces," said Tig. "For me, it’s not an issue. I actually enjoy it!"

Seeking a spot in her third career WTA final, Tig will now face qualifier Tereza Martincova of the Czech Republic in the semifinals, which will be the first meeting between the two. Martincova continued her solid run out of qualifying earlier on Friday, when she claimed a 6-2, 6-3 victory over Aliaksandra Sasnovich of Belarus.

"I’m just trying to focus on [my game], and to fight, like I did in the previous matches, and we will see what’s going to happen," Tig said, looking forward to the semifinal.

Peterson got off to a quick start in the encounter, finding numerous winners down the line as she built a 3-0 lead. However, Tig recovered from there, forcing an error with her backhand to reach triple break point at 3-1, then pulling back on serve at 3-2 after a Peterson double fault. 

The depth of shot from Tig began to steer her to control of the set, as she continued to force errors from Peterson. Another double fault on break point gave Tig a fourth game in a row and a 4-3 lead, and the Romanian kept her run rolling with a strong serve to hold for 5-3.

Serving to stay in the set, an error-forcing forehand by Peterson brought her to game point, but a sturdy Tig return pulled the game to deuce, and the Romanian then earned a set point after a crosscourt forehand winner cracked open a rally. For her third straight service game, Peterson hit an untimely double fault on break point, and Tig had won six games in a row to lead by a set.

A misfired forehand into the net by Tig gave Peterson a service break in the first game of the second set, but that proved to be a rare misstep by the Romanian as she went on a tear from there. The break back was immediately attained in the next game after Tig ended a grueling rally with a passing winner to level the set at 1-1.

After saving a break point with a solid serve to hold for 2-1, Tig went up a double break in the next game after forcing an error with a brilliant crosscourt backhand. Tig then saved three more break points in a protracted game, mixing powerful forehands with delicate dropshots to grit out the hold for 4-1.

Those would be the final chances for Peterson, as the Swede dropped serve with a double fault once more to cede the 5-1 advantage to Tig. The Romanian closed out the match with no fuss, converting her first match point and sailing into the semifinals.

2020 Istanbul highlights: Tig triumphs over Peterson to reach semifinals